ID: Google -- compiled response to 12 Nov 15 interp request -- 4 Feb 16 final

Chris Urmson

Director, Self-Driving Car Project

Google, Inc.

1600 Amphitheatre Parkway

Mountain View, CA 94043

Dear Dr. Urmson:

This responds to your November 12, 2015 letter[1] requesting that the National Highway Traffic Safety Administration (NHTSA) interpret a number of provisions in the Federal Motor Vehicle Safety Standards (FMVSSs) as they apply to Google’s described design for motor vehicles that it is in the process of developing and testing.  According to Google, those self-driving vehicles (SDVs) are “fully autonomous motor vehicles, i.e., vehicles whose operations are controlled exclusively by a Self-Driving System (SDS).”  The SDS is an artificial-intelligence (AI) “driver,” which is a computer designed into the motor vehicle itself that controls all aspects of driving by perceiving its environment and responding to it.[2]  Thus, Google believes that the vehicles “have no need for a human driver.” 

In this response, NHTSA addresses each of Google’s requests for interpretation, and grants several of them.   In some instances, the issues presented simply are not susceptible to interpretation and must be resolved through rulemaking or other regulatory means.  NHTSA believes that many of these issues may be resolved on an interim basis through well-supported exemption petition(s), and invites Google to file such petitions.  In other instances, if Google is able to provide sufficient additional information and evidence, it may be possible to resolve open issues through interpretations.

INTRODUCTION

Google describes its vehicles as having what NHTSA’s May 2013 Preliminary Statement of Policy Concerning Automated Vehicles calls Level 4 Full Self-Driving Automation.  According to that Statement, a Level 4 vehicle

is designed to perform all safety-critical driving functions and monitor roadway conditions for an entire trip. Such a design anticipates that the driver will provide destination or navigation input, but is not expected to be available for control at any time during the trip. This includes both occupied and unoccupied vehicles. By design, safe operation rests solely on the automated vehicle system.

Google is asking for interpretations to determine how it would certify its SDV to the FMVSS.  In essence, Google seeks to produce a vehicle that contains L4 automated driving capabilities, and removes conventional driver controls and interfaces (like a steering wheel, throttle pedal, and brake pedal, among many other things).  Given that the SDS controls all aspects of driving, and given Google’s belief that the SDS consistently will make the optimal decisions for the SDV occupants’ safety (as well as for pedestrians and other road users), the company expresses concern that providing human occupants of the vehicle with mechanisms to control things like steering, acceleration, braking, or turn signals, or providing human occupants with information about vehicle operation controlled entirely by the SDS, could be detrimental to safety because the human occupants could attempt to override the SDS’s decisions.  While the L4 automation is the impetus behind these design decisions, it is Google’s design decisions that create the uncertainty over how to apply the FMVSS to Google’s proposed vehicle. 

Google’s design choices in its proposed approach to the SDV raise a number of novel issues in applying the FMVSSs.  Those standards were drafted at a time when it was reasonable to assume that all motor vehicles would have a steering wheel, accelerator pedal, and brake pedal, almost always located at the front left seating position, and that all vehicles would be operated by a human driver.  Accordingly, many of the FMVSSs require that a vehicle device or basic feature be located at or near the driver or the driver’s seating position.  For vehicles with an AI driver that also preclude any occupant from assuming the driving task, these assumptions about a human driver and vehicle controls do not hold.  As self-driving technology moves beyond what was envisioned at the time when standards were issued, NHTSA may not be able to use the same kinds of test procedures for determining compliance.  And since the Safety Act creates a self-certification system for compliance, NHTSA’s verification of a manufacturer’s compliance (and thus, the agency’s ability to enforce against non-compliance) is based on our established test procedures.

In order to determine where to place vehicle devices and features, or whether to provide them at all, Google has asked who or what is to be considered the “driver” and which seating position is considered to be the “driver’s seating position” in its SDV.  49 CFR 571.3 defines “driver” as “the occupant of a motor vehicle seated immediately behind the steering control system.”  Because Google’s SDV design purposely does not have any mechanism by which human occupants could steer or otherwise “drive” the vehicle, it would be difficult in several instances to determine who the “driver” would be in its SDV, and thus to determine how to certify its motor vehicle design to certain FMVSS provisions that reference that “driver.”  To attempt to solve this challenge, Google has offered different interpretations of “driver” or “driver’s seating position” for NHTSA’s consideration, varying with the specific requirement or circumstances, and requests that we confirm its interpretations.

Specifically, Google suggests two potential interpretations of “driver” and one potential interpretation for “driver’s position” or “driver’s designated seating position” in the context of its described motor vehicle design:

• NHTSA could interpret the term “driver” as meaningless for purposes of Google’s SDV, since there is no human driver, and consider FMVSS provisions that refer to a driver as simply inapplicable to Google’s vehicle design;
• NHTSA could interpret “driver” and “operator” as referring to the SDS; or
• NHTSA could interpret “driver’s position” or “driver’s designated seating position” as referring to the left front outboard seating position, regardless of whether the occupant of that position is able to control the vehicle’s operation or movements.

Google then applies these suggested interpretive approaches to a number of FMVSS provisions in order to justify being able to certify its intended motor vehicle design as compliant with the FMVSSs, without having to change the design in ways that Google finds problematic. 

We will address each of Google’s suggested interpretations in turn.  The critical point of NHTSA’s responses for many of the requested interpretations is that defining the driver as the SDS (or the driver’s position as the left front position) does not end the inquiry or determine the result.  Once the SDS is deemed to be the driver for purposes of a particular standard or test, the next question is whether and how Google could certify that the SDS meets a standard developed and designed to apply to a vehicle with a human driver.  Related, in order for NHTSA to interpret a standard as allowing certification of compliance by a vehicle manufacturer, NHTSA must first have a test procedure or other means of verifying such compliance.

While some of Google’s requested interpretations may be permissible given the facts presented here, we wish to make clear that many of the other requests present policy issues beyond the scope and limitations of interpretations and thus will need to be addressed using other regulatory tools or approaches.  NHTSA further notes that in a number of instances (in particular, several included in Table B), it may be possible for Google to show that certain standards are unnecessary for a particular vehicle design.  To date, however, Google has not made such a showing.  We note that these interpretations are confined to the specific facts and circumstances set forth in Google’s letter, and that they do not apply to other facts and circumstances.  We also emphasize that the interpretations NHTSA is issuing are subject to change or revocation if new or different facts or information comes to light.

DISCUSSION

NHTSA is authorized by the National Traffic and Motor Vehicle Safety Act (“Safety Act,” 49 U.S.C. Chapter 301) to issue FMVSSs that set performance requirements for new motor vehicles and new items of motor vehicle equipment.  Under the Safety Act, NHTSA does not provide approvals of motor vehicles or motor vehicle equipment and does not make determinations as to whether a product conforms to the FMVSSs outside of a NHTSA compliance test.  Instead, the Safety Act requires manufacturers to self-certify that their products conform to all applicable FMVSSs that are in effect on the date of manufacture.  Manufacturers are also responsible for ensuring that their products are free of safety-related defects.  NHTSA enforces compliance with the FMVSSs by testing vehicles and regulated equipment.  NHTSA also investigates safety-related defects and conducts related enforcement and recall actions. 

As a foundational starting point for the interpretations below, NHTSA will interpret “driver” in the context of Google’s described motor vehicle design as referring to the SDS, and not to any of the vehicle occupants.  We agree with Google its SDV will not have a “driver” in the traditional sense that vehicles have had drivers during the last more than one hundred years.  The trend toward computer-driven vehicles began with such features as antilock brakes, electronic stability control, and air bags, continuing today with automatic emergency braking, forward crash warning, and lane departure warnings, and continuing on toward vehicles with Google’s SDV and potentially beyond.  No human occupant of the SDV could meet the definition of “driver” in Section 571.3 given Google’s described motor vehicle design – even if it were possible for a human occupant to determine the location of Google’s steering control system, and sit “immediately behind” it, that human occupant would not be capable of actually driving the vehicle as described by Google.  If no human occupant of the vehicle can actually drive the vehicle, it is more reasonable to identify the “driver” as whatever (as opposed to whoever) is doing the driving.  In this instance, an item of motor vehicle equipment, the SDS, is actually driving the vehicle. 

NHTSA will consider initiating rulemaking to address whether the definition of “driver” in Section 571.3 should be updated in response to changing circumstances, as contemplated by Executive Order 12866, Regulatory Planning and Review.  Section 5, Reducing Regulations, of that Order provides that each federal regulatory agency will

[i]n order … to determine whether regulations promulgated by the executive branch of the Federal Government have become unjustified or unnecessary as a result of changed circumstances …  periodically review its existing significant regulations to determine whether any such regulations should be modified or eliminated so as to make the agency’s regulatory program more effective in achieving the regulatory objectives …

NHTSA recognizes that it can take substantial periods of time to develop some rulemaking proposals and final rules, including time spent obtaining review of those proposals and seeking and analyzing public comments.  NHTSA further understands that the time it takes to conduct rulemakings may, in some instances, make such proceedings ill-suited as first-line regulatory mechanisms to address rapidly-evolving vehicle technologies.  That said, there are limits to the result the agency may reach in an interpretation, even if it believes that result might be sound policy.  An interpretation describes an agency’s view of the meaning of an existing statute or regulation.  It can make sense of the overall legal framework and provide clarity for regulated entities and the public.  For example, an interpretation may clarify a statutory or regulatory term or provide crisper and more detailed lines than the regulation or statute being interpreted.  An interpretation may not, however, make a substantive change to the statutory or regulatory regime or to the clear language of a provision.  In particular, an interpretation may not adopt a new position that is irreconcilable with or repudiates existing statutory or regulatory provisions.   

In many instances, interpreting the term “driver” in a manner that Google has requested does not necessarily change the requirements of the regulation or otherwise fully resolve the issue Google seeks to address. Because the interpretations provided by this letter do not fully resolve all of the issues Google has raised, Google may wish to explore the interim step of seeking exemptions.  Exemptions are available under 49 U.S.C. 30114 and 49 CFR Part 555 for manufacturers able to demonstrate that features of their products provide equivalent levels of safety to those required by the FMVSS.  

1. “Priority Interpretive Issues”

Google requested NHTSA’s interpretation of several “priority interpretive issues” related to the absence of a human driver.  Google also provided two tables, Attachments A and B, listing FMVSS provisions for which Google requested that NHTSA interpret the “driver” or “operator” to be the SDS (provisions in Attachment A) and other provisions for which Google requested that NHTSA interpret “driver” to be the human occupant seated in the left front designated seating position (primarily provisions in Attachment B).  We address these interpretation requests in the order presented by Google’s November 12 letter.

FMVSS No. 135, “Light Vehicle Brake Systems”

Deeming the SDS to be the “driver” of a motor vehicle does not excuse that vehicle from compliance with the brake requirements of applicable standards.  FMVSS No. 135 contains requirements for service brakes and associated parking brake systems.  Among these requirements is S5.3.1, which states that service brakes “shall be activated by means of a foot control,” and also that “control of the parking brake shall be independent of the service brake control, and may be either a hand or foot control.”  Google’s described motor vehicle design does not include hand or foot controls for either the service brakes or the parking brake.  Google argues that because the SDS will control all aspects of braking, it would not be necessary or beneficial for safety for a human occupant to be able to brake the vehicle.  Google therefore requests that NHTSA interpret these provisions regarding the activation or control of braking systems to be inapplicable to its described motor vehicle design.  Similarly, Google requests that NHTSA interpret S6.5.1 of FMVSS No. 135 to allow the service brake system performance requirements to be met if the SDS activates the service brakes, rather than “solely by use of the service brake control” as the provision directs. 

We agree that Google’s SDS may be deemed to be the driver for purposes of compliance with these provisions.  Given that there will be no foot (or even hand) control to be activated – indeed, given that the SDS will have neither feet nor hands to activate brakes – we understand that Google’s described vehicle design would not comply with S5.3.1 as written.  We also understand Google’s assertions that the SDS will be able to activate the brakes electronically such that its vehicle will “stop [] safely and in accordance with all performance requirements of FMVSS No. 135.”  The fact that the SDS may be programmed to perform the tests enumerated in FMVSS No. 135 does not, however, overcome the plain language of S5.3.1.  NHTSA would need to commence a rulemaking to consider how FMVSS No. 135 might be amended in response to “changed circumstances” in order to ensure that automated vehicle designs like Google’s, i.e., ones that control all braking through an AI driver and do not provide brake controls to vehicle occupants, have a way to comply with the standard.  Such a rulemaking would also consider S6.5.1 and any other provisions that implicate the potential use of a foot-actuated service brake control.  In the interim, Google may wish to consider petitioning the agency for an exemption from these provisions.[3]

FMVSS No. 101, “Controls and Displays”

FMVSS No. 101 contains requirements for location, identification, color, and illumination of motor vehicle controls, telltales, and indicators.  S5.1.1 requires the controls listed in Tables 1 and 2 of the standard to be “located so that they are operable by the [belted] driver.”  S5.1.2 requires the telltales and indicators in those Tables and their identification to be “located so that, when activated, they are visible to a [belted] driver.”  Google states that its motor vehicle will not have any of the controls listed in Tables 1 and 2 because there will not be a human driver in its vehicle.  Further, Google believes that allowing the human occupants to affect the operation of, for example, lamps or turn signals otherwise controlled by the SDS could be detrimental to safety.  Google therefore asks that NHTSA interpret S5.1.1 to be inapplicable to its motor vehicle design, or that NHTSA interpret Google’s SDS to be the “driver” for the purposes of S5.1.1.  For S5.1.2, Google says it will equip its vehicle’s occupant compartment with the telltales and indicators required by other FMVSSs (like the telltales/indicators for malfunctions of the brake system, electronic stability control system, or tire pressure monitoring system).  For purposes of placement of those telltales and indicators, Google requests that NHTSA interpret the “driver position” to be the left front seating position.

Because we interpret “driver” as referring to the SDS, we agree with Google that the controls listed in Tables 1 and 2 may simply be operable by the SDS and need not be located so that they are available to any of the human occupants of the motor vehicle.  Similarly, telltales and indicators must also be “visible” to the SDS.  For purposes of both S5.1.1 and S5.1.2, we interpret the SDS to be the “driver.”  However, we have no defined way at this time of verifying Google’s compliance with this interpretation of these requirements.  Thus, if Google certified its compliance with these provisions consistent with this interpretation, NHTSA would be unable to conduct confirmatory testing to satisfy ourselves that the Google vehicle is compliant.  Therefore, unless and until NHTSA has a standard and testing procedures to confirm compliance with S5.1.1 and S5.1.2, or a standard providing equal or greater safety, it cannot conclude that Google’s SDV is compliant with those requirements.  In order to determine what “operable by” and “visible to” the SDS mean, and to establish procedures for testing compliance with those requirements using its existing regulatory tools, NHTSA would be required to conduct a rulemaking.

In the interim, Google may wish to petition the agency for an exemption from these provisions.[4]  Additionally, we agree with Google that it could be beneficial to vehicle occupants to be aware of certain aspects of vehicle status through telltales and indicators while they are traveling in the vehicle.  Given the historical status of the left front seating position as the location of the human in charge of vehicle operation, we agree that Google may voluntarily locate telltales and indicators so that they are visible to that position.  However, if it is foreseeable that a different seating position is more likely to be occupied, it may make more sense for the telltales and indicators to be located so that they are visible in another position.

FMVSS No. 108, “Lamps, Reflective Devices, and Associated Equipment”

FMVSS No. 108 contains requirements for original and replacement lamps, reflective devices, and associated equipment.  Google states that it “recognizes that all vehicles must comply with all of the performance requirements of FMVSS No. 108 with respect to external lamps and reflectors,” but asks that NHTSA interpret S6.6.1 of FMVSS No. 108 to allow certain internal controls “to be excluded from the occupant compartment, as long as their functions are performed by the vehicle autonomously.”  S6.6.1 requires all vehicles covered by FMVSS No. 108 to be “equipped with a turn signal operating unit, a turn signal flasher, a turn signal pilot indicator, a headlamp beam switching device, and an upper beam headlamp indicator meeting the requirements of S9.” 

With respect to turn signal operating units, Google requests that NHTSA interpret the term “operator” in the S4 definition of “turn signal operating unit” to mean the SDS.  That definition states that the unit is “an operating unit that is part of a turn signal system by which the operator of a vehicle causes the signal unit to function.”  Google notes that, in its vehicle, the turn signals will be operated and controlled by the SDS.  Google’s letter also addresses S9.1.1, which requires that the “turn signal operating unit…must be self-canceling by steering wheel rotation and capable of cancellation by a manually operated control.”  Google requests that NHTSA interpret this provision to be met by Google’s SDS since there would not be any steering wheel or conventional turn signal stalk.  Google also argues that providing either a steering wheel or the ability to control turn signal operation to the vehicle occupants could be detrimental to safety.  Google further asks that NHTSA “expressly acknowledg[e]” that a steering wheel is not required by the FMVSS.  The supplemental information Google provided on January 11, 2016 stated that the SDV’s turn signal operating unit self-cancels based on the position of the steering rack (which is controlled by the SDS), “which is what happens in a conventional vehicle by virtue of the link between the steering rack, steering column, and steering wheel,” and that Google therefore believes that the SDV complies with S9.1.1.

With respect to the S9.4 requirement for headlamp beam switching devices, which provides that “[e]ach vehicle must have a means of switching between lower and upper beams designed and located so that it may be operated conveniently by a simple movement of the driver’s hand or foot,” Google again states that the SDS will control headlamp beam switching “fully and appropriately” and that human occupant control over such functions could be detrimental to safety.

For purposes of these provisions of FMVSS No. 108, we interpret the SDS to be the “driver.”  We also agree that the “operator” of a turn signal operating unit is the SDS, because NHTSA has typically used “driver” and “operator” interchangeably in its interpretations over time.  We further agree that a steering wheel is not expressly required by any FMVSS.  We agree with Google that, as described, the SDV appears to be designed to self-cancel the turn signal operating unit as NHTSA would have intended, had vehicles without steering wheels been available when FMVSS No. 108 was developed.  Similar to the provisions of FMVSS No. 135, however, the fact that the SDS may be programmed to cancel the turn signal and switch headlamp beams does not overcome the (other) plain language of S9.1.1 and S9.4.  Even if we agree that Google’s self-cancelation for the turn signal operating unit is consistent with our intent in S9.1.1., that provision further expressly requires that the turn signal be capable of cancellation by a “manually operated control.” We understand Google’s argument that in the case of the SDV, manual cancelation of the turn signal operating unit by a human occupant could interfere with decisions already made by the SDS in ways that could affect safety.  However, this is an issue that cannot be addressed through interpretation alone.  Similarly, S9.4 specifically requires operation of headlamp switches by movement of the “driver’s hand or foot”.[5]  Under existing test procedures, we cannot verify Google’s compliance with these express requirements. 

Unless and until NHTSA has a standard and testing procedures to confirm compliance with these provisions, it cannot interpret Google’s SDV as compliant with these standards and requirements.  In order to determine what requirements would be appropriate, and to establish procedures for testing compliance with those standards, using its existing regulatory tools, NHTSA would be required to conduct a rulemaking.  NHTSA would need to consider how it could propose to amend FMVSS No. 108 in order to ensure that automated vehicle designs like Google’s, i.e., those that control all lighting and signals through the AI driver and do not provide lighting or signal controls to vehicle occupants, have a way to comply with the standard.  Meanwhile, Google may wish to petition the agency for an exemption from these provisions.  An exemption petition could seek to demonstrate that Google’s SDV would provide an equivalent level of safety to that provided by compliance with the FMVSS.[6] 

1. Interpretive Issues regarding “Miscellaneous Provisions in Other FMVSS”

Google also requested interpretation of several other “miscellaneous provisions in other FMVSS” relating to the absence of a human driver.

FMVSS No. 111, “Rear Visibility”

FMVSS No. 111 contains requirements for rear visibility devices and systems, requiring that vehicles have external and internal rear view mirrors to provide the driver with certain fields of view around and behind the vehicle.  FMVSS No. 111 also requires that vehicles display a rearview image (of a specified area of certain dimensions behind the vehicle) to the vehicle operator.  Google asks that NHTSA interpret these provisions as requiring that the specified view be provided to the SDS, rather than to the human occupant.  Google further requests that “the vehicle would be deemed compliant if the SDS receives sensor input at least equivalent to the images a driver would be able to view through mirrors and a rear visibility system meeting the field of view and other performance requirements of the standard.”

As above, because we are interpreting “driver” and “operator” in this instance to refer to the SDS, we agree that the information required by the provisions of FMVSS No. 111 that must be provided to the “driver” or “operator” may be provided to the SDS.  Here again, we have no defined way at this time of verifying Google’s compliance with this interpretation of those requirements.  Thus, if Google certified its compliance with these provisions consistent with this interpretation, NHTSA would be unable to conduct confirmatory testing to satisfy ourselves that such certification was valid. 

Therefore, unless and until NHTSA develops and adopts appropriate performance criteria and test procedures for evaluating whether the sensor input received by the SDS provides enough information to ensure that the SDS is as well informed by its sensors of the conditions behind and around it as a human driver of a conventional vehicle that meets the existing requirements of FMVSS No. 111 (or a standard providing equal or greater safety), it cannot interpret Google’s SDV as compliant with these standards and requirements.  This would need to be undertaken through rulemaking.  NHTSA may also consider as part of such a rulemaking whether there is benefit to conveying this information to human occupants in the case of vehicle designs like the Google SDV.  Google may wish to petition the agency for an exemption from these provisions, in which it could seek to demonstrate that its SDV would provide an equivalent level of safety to that provided by compliance with the FMVSS.[7] 

FMVSS No. 114, “Theft Protection and Rollaway Prevention”

FMVSS No. 114 contains requirements intended to reduce the incidence of crashes resulting from theft and accidental rollaway of vehicles.  Among these requirements is S5.3, which requires vehicles with an automatic transmission that includes a “park” position to have a system that “requires the service brake to be depressed before the transmission can be shifted out of ‘park.’”  Google states that its vehicle will not have any brake pedal, and that its SDS “will determine the appropriate transmission position and will not select a position other than park unless the service brake is first applied by the SDS.”  Google therefore requests that NHTSA interpret S5.3 as met by this described approach.

We agree that the language of S5.3 requiring the service brake to be depressed does not necessarily require the service brake itself to be pressed or applied by any particular object or function, such as a human foot.  We also agree that if the SDS is controlling the service brake, in theory, it would be able to make the decisions that would accomplish the intent of this provision.  In order for NHTSA to assess compliance of Google’s vehicle with this standard, however, we would need more information regarding how the SDS applies the service brake.  We would also intend to develop and adopt through rulemaking performance standards and test procedures for evaluating how (for example) the SDS “determines the appropriate transmission position” and avoids “selecting a position other than park unless the service brake is first applied.”  NHTSA might also consider as part of such a rulemaking the safety intent of the standard, and how human occupants should be protected when the vehicle is making decisions about when to initiate movement.  Google may wish to petition the agency for an exemption from these provisions.[8] 

FMVSS No. 126, “Electronic Stability Control Systems”

FMVSS No. 126 contains performance and equipment requirements for electronic stability control (ESC) systems.  Google argues that because its vehicle will not have a steering wheel, and the SDS will control all aspects of steering, NHTSA should interpret the relevant provisions of FMVSS No. 126 “to allow compliance with the performance requirements of the standard to be tested on the basis of appropriate steering inputs provided by the SDS.”  Google cites in particular the definition of an ESC system in S4 as referring to “a means to monitor driver steering inputs” and the test conditions in S6 and test procedures in S7, which refer to steering wheel velocity and angle.

Test procedure provisions in S7 (such as S7.5.2, S7.5.3, S7.6, S7.6.1, S7.9.3, and others) refer specifically to measurement of “steering wheel angle,” which is, literally, a measurement of the angle of the steering wheel in degrees.  Without a steering wheel, we agree that Google cannot certify its vehicle design to such provisions.  As above, in order for NHTSA to assess compliance of Google’s vehicle with this standard, we would need to determine how to evaluate the SDS’ control of the steering inputs, and whether and how to modify test conditions and procedures to address more clearly the situation of a vehicle with steering controlled entirely by an AI driver, with no mechanism for the vehicle occupants to affect the steering.  Google could petition for exemption from the relevant provisions of FMVSS No. 126

and the agency could work to develop alternate test procedures.  Over the longer term, NHTSA would need to undertake rulemaking to incorporate test procedures into FMVSS No. 126 to provide a clearer path to compliance for similar future vehicle designs.

Google’s letter concludes with two attachments, summarily listing numerous additional provisions for which it seeks interpretation.  Attachment A lists “Requirements for which the ‘Driver’ or ‘Operator’ should be considered to be the Self-Driving System.”  The letter provides no further explanation or justification for those requested interpretations.  Attachment B provides a similar list of FMVSS “Requirements for which the ‘Driver’ should be considered to be a person seated in the left front designated seating position.”  We address these numerous items in Attachments A and B in Tables A and B, to this letter, respectively (attached).  The Tables in those attachments reproduce each of Google’s requests in the first three columns, and provide NHTSA’s response in the final column.

In closing, we note that, in some instances, it may be possible for Google to provide more information and explanations that would allow NHTSA to expand or otherwise revise interpretations set forth in this letter.  If Google believes it can address concerns and limitations expressed in this letter that prevent us from providing the full interpretation it seeks, we encourage the company to submit more information to do so. In addition, as discussed above, Google may wish to seek exemptions from standards and requirements addressed in this letter. I hope this information provided in this letter and its attachments is helpful.  If you have further questions, please feel free to contact me at (202) 366-2830, or Steve Wood, Assistant Chief Counsel for Vehicle Safety Standards and Harmonization, at (202) 366-2992.

                                                                        Sincerely yours,

                                                                        Paul A. Hemmersbaugh

                                                                        Chief Counsel

III.  Table A

NHTSA interprets the SDS to be the “driver” or “operator” for the following specific FMVSS provisions.  As discussed above, we have no defined way at this time of verifying Google’s compliance with this interpretation of these requirements.  Thus, if Google certified its compliance with these provisions consistent with this interpretation, NHTSA would be unable to conduct confirmatory testing to satisfy ourselves that such compliance was valid.  Therefore, unless and until NHTSA develops performance criteria and test procedures for evaluating whether the SDS satisfies the FMVSS provision in question to be met, or a standard providing equal or greater safety, it cannot interpret Google’s SDV as compliant with these standards and requirements.  Google may wish to petition the agency for exemption from these petitions in the interim.

1. Table B

For specific FMVSS provisions set forth on Google’s Attachment B, Google requested that NHTSA interpret the human occupant seated in the left front designated seating position (‘DSP’) as the “driver.”  As discussed above, NHTSA defines “driver” for purposes of the FMVSS at 49 CFR 571.3.  We also discuss above the need to amend that definition in light of the possibility that Google raises, that an AI driver could be the sole means of driving a vehicle.  Given the focus of the definition of “driver” as, essentially, the entity that controls steering, and given that Google’s proposed vehicle design gives the human occupant no means to steer the vehicle, the human occupant of the left front DSP could not be the driver.  Moreover, interpreting “driver” as the human occupant of the left front DSP in the instances below that Google cites would not, in most cases, provide Google with a means of certifying that its proposed vehicle design complies with the applicable standard, because the agency would need to establish standards and tests to verify that the design complies. 

It may be that for some of these provisions, the elimination of a human driver makes the provision unnecessary, as Google implies in its letter.  NHTSA will consider these issues further and looks forward to receiving additional information from Google to assist us in this consideration.  For the following provisions, we are therefore continuing to interpret “driver” as referring to the SDS, and discuss what steps would need to be taken next in order to provide a path forward:

[1] Google also submitted a supplemental letter date January 11, 2016, providing more detailed information on its approach to canceling the turn signal, which is discussed below.

[2] NHTSA considers this AI driver to be an item of motor vehicle equipment within the meaning of 49 U.S.C. 30102 and other applicable law and regulations.

[3] Google may also wish to reconsider its view that a pedal may never be needed in any circumstance, and that there is not a risk of harm associated with a pedal’s absence.

[4] Google may also wish to reconsider its view that the controls listed in Tables 1 and 2 of S5.1.1 may never be needed in any circumstance, and that there is not a risk of harm associated with their absence.

[5] We note that S9.4.1 of FMVSS No. 108 provides a mechanism by which a manufacturer can certify a “semi-automatic headlamp beam switching device,” but Google did not ask for interpretation of this provision, nor do we have enough information to assess whether Google’s proposed design would comply with this provision.

[6] Google may also wish to reconsider its view that a steering wheel and the vehicle occupants’ ability to control any lighting and signals may never be needed in any circumstance, and that there is not a risk of harm associated with their absence.

[7] Google may also wish to reconsider its view that rear visibility devices and systems may never be needed in any circumstance, and that there is not a risk of harm associated with their absence.

[8] Google may also wish to reconsider its view that a pedal may never be needed in any circumstance, and that there is not a risk of harm associated with a pedal’s absence.

[9] We note that NHTSA has previously interpreted this provision as prohibiting automatic (i.e., non-driver initiated) control of turn signal lamp flashing, but we do not consider this interpretation as inconsistent with those, because in this instance we are interpreting the “driver” (the SDS, given that the human occupants have no mechanism by which they can drive the vehicle) as being the entity controlling the vehicular hazard warning signal operating unit.  NHTSA would like to explore further with Google the instances in which Google would intend for the SDS to flash the hazard warning signals.

ID: 99aiam3.ogm

Mr. George L. Parker
Association of International Automobile Manufacturers
1001 19th St. North
Suite 1200
Arlington, VA 22209

Dear Mr. Parker:

The Associate Administrator for Safety Performance Standards, L. Robert Shelton, has asked me to respond to several concerns that the Association of International Automobile Manufacturers (AIAM) has raised in both correspondence and in a meeting with the agency on August 19, 1998, regarding the interpretation of Standard 201, Occupant Protection in Interior Impact, and the compliance test procedures for that section. Your letter asks that the agency:

• again consider limiting multiple impacts in cases in which target areas are near each other,
• clarify the definition of "convertible roof frame" in the context of Standard 201,
• provide guidance on the position of sun roofs for targeting purposes,
• clarify the procedure for relocating target areas when those targets must be moved, and
• address what AIAM considers to be unacceptable potential variability between target area locations as derived by manufacturers for certification testing and by the National Highway Traffic Safety Administration (NHTSA) for compliance testing.

In the August 19, 1998, meeting, AIAM and other industry participants presented additional information relating to multiple impacts. They also raised issues concerning lower face and cheek contact during testing, and procedures for relocating targets in the event that movable seat backs make a target area inaccessible for testing.

Multiple Impacts

Your letter indicates that AIAM shares the concern raised by the (former) American Automobile Manufacturers Association (AAMA) regarding multiple impacts and that you wish to raise an additional point on this issue. As your letter indicates, AAMA filed a petition for reconsideration in response to the April 8, 1997, final rule modifying the head impact provisions of Standard 201. The AAMA petition, filed on May 23, 1997, requested in part that the agency consider limiting impacts for certain target areas to one impact per individual piece of trim. In its petition, AAMA contended that test impacts may result in damage to trim components that may extend beyond the area in the immediate vicinity of the impact point. AAMA also stated that impacts by the lower face and other portions of the Free Motion Headform (FMH) that are outside of the forehead impact zone may also damage trim so that the ability of the vehicle to withstand an impact at an adjacent target area is compromised. Your letter refers specifically to the potential for an impact by the lower face to cause collateral damage to a second target area when the first is being tested. You state that the lower face and the forehead impact zone of the FMH are approximately 200 millimeters apart and that the existing limitation in S8.14(c) excluding impacts into target areas that are separated by 150 mm or less does not preclude a second impact into a target area that has been damaged by lower face contact resulting from an impact to a nearby target area. Due to this phenomenon, you argue that impacts should be limited to one impact per component.

As you are undoubtedly aware, NHTSA published a denial of the AAMA petition on April 22, 1998. (63 FR 19839) In denying the AAMA petition, the agency noted that AAMA had not submitted any data supporting its position and that the agency continued to believe that the 150 mm minimum distance between target areas was sufficient to prevent overlapping impacts. Accordingly, NHTSA denied the AAMA request to limit impacts to one impact per component.

AAMA presented additional data relating to the consequences of contact between lower portions of the Free Motion Headform and interior trim components during the August 19, 1998, meeting. These data indicate that contact between the lower portion of the FMH and interior trim during testing of one target area may degrade the performance of the trim in the area of the contact to an extent that it may be difficult, if not impossible, for the vehicle to meet the specifications of Standard 201 when tested at a target area in the vicinity of the lower face contact.

The agency recognizes that Standard 201 does not require that a component sustain multiple impacts at a single target area without any degradation in performance. S8.14(c) currently provides that no impact may occur within 150 mm of another impact. This distance was selected because of the possibility that collateral damage could occur when the forehead impact zone of the FMH, which is 125 mm wide, makes contact with an intended target point. In setting this distance, NHTSA did not consider the length of the FMH as well as its width. The agency will initiate rulemaking to consider the possibility of amending the Standard to provide that on certain vertical interior surfaces, notably pillars, roll bars and stiffeners, a target area that is within 200 millimeters of another target area, measured from the center of each target, that has been impacted by the FMH during a compliance test shall be not be tested. The proposal would be limited to vertical surfaces since lower face impacts are most likely to occur on vertical surfaces where the distance between the lower face and the forehead impact zone becomes an issue. However, in cases in which a target on one side of the vehicle is not used because of its proximity to another impact area, the corresponding target on the other side of the vehicle will be used. By testing in this fashion, the agency will be able to test all target points to the requirements of Standard 201 without requiring that targets meet these requirements in multiple impacts.

Lower Face Contact and HIC Calculation

Another item of concern discussed at the August 19, 1998, meeting was the effect of lower face or cheek contact on the measurement of compliance with the Head Injury Criterion (HIC) specified for Standard 201. AIAM, AAMA and others are concerned that, in a number of test configurations, the lower portion of the FMH "face" contacts the vehicle interior either at the same time or very shortly after the forehead impact zone of the FMH contacts a target area. They allege that the contact between the lower portion of the FMH "face" and the vehicle interior in these circumstances results in additional acceleration that may cause the resultant HIC to be higher than it would be if the contact were between the forehead impact zone and the intended target area alone. AAMA recommended that in cases in which the injury reference values are exceeded during compliance testing and it is subsequently determined that early lower face involvement is the cause, the test be rerun with an increased off-set angle sufficient to create an identifiable degree of separation time between forehead impact and the lower face contact. Data developed by General Motors and presented at the August 19, 1998, meeting were used to support the contention that an off-set angle of 25 degrees is needed to delay lower face impact beyond the HIC calculation time period. During that same meeting, Mitsubishi presented an example of a series of tests in which impacts to an upper roof target area resulted in contact between the lower face of the FMH and a nearby B-pillar target, BP-1. According to Mitsubishi, the lower face contact occurred within 6 milliseconds of the forehead striking its intended target, and the accelerations resulting from both impacts could not be distinguished. The result of these two cumulative impacts was purportedly to increase the HIC score to fifty percent above that measured when no lower face contact occurred.

NHTSA does not intend to initiate rulemaking to increase the offset angles beyond those currently contained in Standard 201. In the August 18, 1995, final rule establishing new specifications for Standard 201 (60 FR 43031), the agency indicated that the final rule allowed a five degree lower face offset for targets on the A-pillar and other targets that are not pillars and a ten degree offset for any other pillar. The offset angle provisions were inserted into Standard 201 after several manufacturers submitted comments indicating that early lower face contact could change measured acceleration levels when compared to impacts on an identical target in which lower face contact did not take place. Tilting the FMH in this fashion would create an offset clearance that would delay lower face contact beyond the time of the HIC calculation, which NHTSA found occurred within 20 milliseconds. The five and ten degree offset angles also did not fundamentally alter the kinematics of the FMH other than to delay lower face contact, so that the safety consequences of allowing the use of these angles were not significant. As inserting the five and ten degree offset angles did not have real safety consequences, the agency felt it was appropriate to do so.

Although the data presented at the August 19, 1998, meeting indicate that the existing five and ten degree offsets may not be sufficient to prevent lower face contact during the time of HIC calculation, the agency has reconsidered its earlier position implying that accelerations from lower face contact occuring within 20 milliseconds of forehead impact should not be included in the HIC score. NHTSA has reviewed the research data used during development of Standard 201 to construct the transform function used in calculating HIC when the FMH strikes a vehicle interior. These data include the results from testing in which the FMH was launched into padded and unpadded surfaces mounted at different angles to represent the interior of a vehicle. In some of these impacts, portions of the lower face of the FMH struck portions of the target structure during the period in which the HIC calculation was taking place. As these data were used to develop the method of determining HIC scores in Standard 201, consideration of the effects of impacts of the lower front surface of the FMH on interior surfaces has already been integrated into the transform function. Because the transform function provides the means for determining HIC when the FMH strikes an interior surface, any implication that lower face contact should not be allowed during the time of the HIC calculation because that contact would improperly influence HIC, is contrary to the research data used in developing the Standard. Accordingly, lower face impacts should be included in Standard 201's evaluation of vehicle performance in those instances in which lower face contact results in a higher HIC score.

In real-world crashes, contact between the vehicle interior and portions of the head other than the forehead is common. The agency believes that the interests of safety demand that countermeasures be developed so that impact accelerations do not produce a HIC greater than 1000 in those instances in which the impact occurs over a larger area of the head. While the offset angles now contained in Standard 201 do not significantly reduce impact speed or the kinetic energy resulting from impact, further increases in the lower face offset could have significant safety consequences. Adopting a 25 degree offset, as suggested by AAMA, would reduce the effective impact speed of the FMH by 10 percent and the kinetic energy of the impact by 18 percent. In addition, allowing the FMH to rotate freely during HIC calculations would also dissipate a small portion of the total kinetic energy. Adopting AAMA's recommendation would be equivalent to a 20 percent reduction in the intended allowable impact energy.

While our review of the underlying data indicates that the use of any offset angles is unnecessary, NHTSA does not presently plan to initiate rulemaking to eliminate the existing offsets, as retaining them does not have any negative impact on safety. Increasing the present offset angles beyond that which is currently specified in Standard 201 could, however, have significant safety consequences. The agency is therefore retaining the existing offset angles and is rejecting the suggestion that they be increased.

Impacts with Glazing

Chrysler engineers presented a front header impact test at the August 19, 1998 meeting in which the FMH struck a front header target and then glanced off the target and contacted the windshield. The particular configuration of the front header and the windshield resulted in the FMH striking the target area at a relatively shallow angle, making a glancing impact with the target area, and then contacting the windshield. The resultant HIC was over 1000, while subsequent impacts to the front header which did not involve the FMH striking the windshield produced a HIC of less than 1000.

Standard 201 is not intended to prevent injuries resulting from impacts with glazing. The current test procedure provides that during testing, window glass is to be placed in the down position. In the case of stationary glazing, such as windshields, rear windows, fixed quarter windows or glazing other than sun roofs, it may not be possible to move the glass to prevent impacts with the FMH when an adjacent target area is tested. If the glazing cannot be moved and the anterior portion of the FMH strikes the glass near or at the same time that the forehead impact zone strikes the target, and thereby affects the HIC, NHTSA will regard the test as invalid.

Definition of Convertible Roof Frame

Your letter also asks that NHTSA clarify the definition of "convertible roof frame" as used in S6.3(a) of Standard 201. That section defines "convertible roof frame" as the "frame of a convertible roof." Section 6.3(a) excludes convertible roof frames and roof linkage assemblies from meeting the impact requirements of S6.1 through S6.2. You wish to know if the definition of "convertible roof frame" includes cross members and braces as these components can be considered to be part of the roof frame and suggest that "cross members and roof braces should be excluded because they are difficult to target and test. . ." because they would tend to vibrate or deflect with impact. Finally, you indicate that these structures "are not likely to offer significant head impact risk."

Under common usage, a frame is considered to be a rigid structure formed of relatively slender pieces joined together to provide major support to a building or structure. Under the commonly accepted meaning of "frame," the cross members and braces of a convertible roof would be considered to be part of the "frame" as they are integrated into the larger structure that provides shape and support for the roof itself. Accordingly, as convertible roof frame is presently defined in Standard 201, such braces and cross members are, by definition, excluded from testing.

AIAM is also concerned about hard top convertible roofs. The agency addressed the issue of hard top convertible roofs in its April 22, 1998, denial of the petition filed by ASC, Incorporated.

As indicated in that notice, NHTSA believes that integrated or hard top convertible tops can and must meet the requirements of Standard 201.

Window and Sunroof Position for Targeting and Impact Testing

As observed in your letter, S8.2(c) of Standard 201 indicates that movable sun roofs are placed in the fully open position for compliance testing. However, the Standard does not address the position of movable sun roofs for targeting. AIAM asks if movable sun roofs are placed in the open or closed position for targeting purposes and suggests that NHTSA intended that movable sun roofs be placed in the closed position when targets are located. This conclusion is based on AIAM's view that certain targets, such as the front header target (FH2) could be located at the sunroof opening. AIAM believes that if this target is located on a sunroof opening with the sunroof open, manufacturers would have to test using test configurations in which the head form would travel through an area above the roof line prior to impact. In AIAM's view, such a test configuration "would not be realistic in the real-world" and goes beyond the intent of the Standard to provide protection against the "interior" head impact.

NHTSA believes that those targets that may be located at a sunroof opening should be located with the vehicle in the same condition as during testing. The sunroof should therefore be in the open position. The agency does not share AIAM's view that this procedure is contrary to the intent of the Standard or would produce an absurd result. Pursuant to S8.13, the headform may be launched against a target from any point inside the vehicle, limited only by the approach angle limits specified for that target. While the use of certain vertical approach angles may result in a portion of the head form traveling along a path above the roof line of the vehicle as it travels from a point inside the vehicle, the agency believes that the likelihood of this occurring is small. NHTSA also observes that as the headform originates inside the vehicle, such an impact could occur in real world impacts.

Measured Along the Vehicle Interior Requirement

As set forth in the August 18, 1995 final rule, S8(b) contained the procedure for relocating targets when it was not possible for the forehead impact zone of the FMH to contact a target. That procedure specified that the target could be relocated to any point within a 25 mm circle, measured along the vehicle interior, from the center of the original target. Your letter states that the April 8, 1997, final rule, which amended the procedures in S8(b) (and redesignated the section as S10(b)) for relocating target areas, modified the relocation procedure to allow movement within a sphere rather than a circle. You observe that the procedure continues to provide that the radius of sphere is determined by measuring from the center of the original target area along the vehicle interior and contend that this directive is inconsistent with the April 8, 1997, amendment, as that amendment changed the acceptable relocation area from a circle to a sphere. In your view, measuring the radius of this sphere along the interior would defeat the purpose of specifying a sphere rather than a circle.

We agree with your view. The existing language's specification that the distance be measured along the vehicle interior, which restricts the measurement to following the contour of an interior surface, is not consistent with the use of a sphere for relocating targets. Accordingly, the agency has deleted the reference to "measured along the vehicle interior" found in S10(b) through a technical amendment.

Variability in the Location of Head Impact Target Areas

Your letter also voices AIAM's concern that neither Standard 201 or the compliance test procedure addresses the potential for variation in the location of target areas as determined by manufacturers and the agency when compliance testing is performed. AIAM indicates that the potential for variation between both vehicles and target locations when performed by different parties jeopardizes the ability of manufacturers to certify their vehicle with a high degree of confidence. To address this difficulty, AIAM suggests that NHTSA specify an allowable variation within the 12.7 mm diameter size of the target marker and adopt a set of procedures for the agency to follow in locating target areas. In this suggested procedure, the agency would locate target areas through obtaining drawings of the target areas for a vehicle from the manufacturer and then reach a mutual agreement with the manufacturer regarding the "correct" target locations prior to any agency testing. Once this procedure is concluded, you also urge the agency to further reduce the potential for variations by using the manufacturer's drawings to locate the seating anchorage points to serve as a reference for locating targets with the use of a coordinate measuring machine. AIAM also suggests that a coordinate measuring machine be used to locate CGF1, CGF2, and CGR, reference points that are located in mid-air, to limit inaccuracies that may result from inaccuracies from other measurement and location methods.

The agency acknowledges that the potential for variation between the location of target areas as determined by the manufacturer and the agency exists. NHTSA is also aware that a certain degree of variation may occur between different vehicles manufactured to the same design. Nonetheless, the agency declines to adopt the procedures suggested in your letter. It is the intent of Standard 201 to ensure that proper protection is provided by the various components addressed by the standard and not merely a few target points. In adopting target points rather than zones, the agency rejected the argument that even zones would create unduly burdensome test conditions. (60 FR 43037). Moreover, the existing procedures for locating target areas were carefully developed by the agency and further refined since their inception to address manufacturer arguments that use of larger target areas would require an extensive amount of testing to verify compliance. While some degree of variation between different examples of the same vehicle or between target locations fixed by different entities performing tests is inevitable, NHTSA believes that such variations are not likely to be unpredictable or large. If the agency were to use manufacturer supplied drawings to locate target areas for compliance testing, it would be providing manufacturers with an undue degree of control over the compliance testing process and acting in derogation of the overall purpose of the Standard. It is the manufacturer's responsibility to assure compliance within the range associated with the target points.

The agency observes that the Standard 201 laboratory test procedure contains certain tolerances which, to a degree, address the issue of variability. However, your member companies should be advised that test procedures are not rules, regulations or agency interpretations regarding the meaning of a safety standard and are not intended to limit the requirements of any applicable standard.

Movable Seat Backs

During the August 19, 1998, meeting, concerns were also raised about the possibility of movable seat backs preventing access to target areas and preventing contact between the forehead impact zone of the FMH and the intended target. It is the agency's position that in the case of potential interference between a movable seat back and a target area, the movable seat back should be placed in any adjustment position that may be attained while the vehicle is in motion.

Accordingly, if a seat back may be reclined for comfort or is hinged to allow ingress or egress to an area of the vehicle, targeting and testing of target areas near that seat back will be conducted with the seat back in any position within the range of adjustment or movement.

I hope that this is responsive to your inquiry. If you have any questions, please contact Otto Matheke of this office at (202) 366-5253.

Sincerely,
Frank Seales, Jr.
Chief Counsel
ref:201
d.2/19/99

ID: 16-000385 -- 49 CFR Part 581 - Response to Alliance Global

ID: 21292

Mr. Vernon H. Rye
Director of Engineering
B & D Independence Co. Inc.
214 S. Market Street
Mt. Carmel, Il 62863





Dear Mr. Rye:

This responds to your letter concerning Federal Motor Vehicle Safety Standard No. 207, Seating systems, and Federal Motor Vehicle Safety Standard No. 210, Seat belt assembly anchorages, as they apply to a product manufactured by your company. The product, designated in your letter as the "Power Transfer Seat Base" (PTSB), is described by you as an adjustable seat pedestal that has the capability to move in as many as ten directions of motion. The PTSB, which is intended for use in full size vans and minivans adapted for people with disabilities, is a power-driven device that allows a person in a wheelchair or scooter to transfer themselves into and out of the original (OEM) seat. You indicate that the PTSB is bolted to the vehicle floor and the OEM seat is bolted to the PTSB in place of what you describe as the OEM seat "pedestal."

Your letter states a number of concerns you have regarding the PTSB and compliance with the requirements of Standards No. 207 and No. 210. You note that the PTSB has the ability to move the seat, and therefore the driver, so far toward the rear of the vehicle that existing seat belt anchorage locations would become ineffective and the driver would most likely not be able to reach any of the vehicle controls. The PTSB may also raise the seat so far up that an occupant would be above the position where a deploying airbag would provide adequate protection in a frontal crash. You also state that due to the large number of adjustments possible with the PTSB, defining the range of adjustments for testing under Standard No. 207 might be confusing or difficult. In addition, you ask 17 questions regarding the definition of certain terms used in these standards. You also ask, in light of the capability of the PTSB to move the seat beyond the range of adjustment provided by the OEM seat assembly, where the PTSB, the OEM seat, and all adjuster mechanisms need to be positioned to conduct "static pull tests" under Standards No. 207 and No. 210. Finally, your letter contains a number of suggestions for amendment or clarification of the foregoing standards. Our response to the issues raised by your letter and the questions and concerns therein are provided below.

Before addressing your specific concerns, I would like to state, by way of background information, that the National Highway Traffic Safety Administration (NHTSA) does not grant approval of motor vehicles or motor vehicle equipment. Under Chapter 301 of Title 49 of the United States Code (49 U.S.C. '30101 et seq.), it is the responsibility of the manufacturer to ensure that its vehicles or equipment comply with all applicable requirements at the time of the item's first retail sale. In this instance, the two standards referred to in your letter, Standard No. 207 and Standard No. 210, are vehicle and not equipment standards. Therefore, responsibility for compliance with these two standards lies with the manufacturer of the vehicle and not the manufacturer of the equipment incorporated into the vehicle.

I also note that the equipment manufactured by your company appears to be intended to modify completed vehicles in order to accommodate the needs of persons with disabilities. In the case where such modifications are performed prior to the first purchase of the vehicle for purposes other than resale, the person performing the modifications to the vehicle would be required to certify that the modified vehicle met all applicable safety standards affected by the alterations (See 49 CFR 567.7). In the case where the modifications are performed after the first sale of the vehicle, the person performing the modifications must ensure that they do not violate a statutory provision that prohibits certain entities from making certain equipment and features inoperative. Specifically, manufacturers, distributors, dealers, and repair businesses may not knowingly make inoperative any part of a device or element of design installed in or on a motor vehicle that is in compliance with an applicable standard (49 U.S.C. '30122). We have interpreted the term "make inoperative" to mean any action that removes or disables safety equipment or features installed to comply with an applicable standard, or that degrades the performance of such equipment or features. Violations of this provision are punishable by civil penalties of up to $5,000 per violation.

Accommodating the special needs of persons with disabilities frequently requires modifications to a vehicle. These modifications frequently require the modification or removal of required safety features. In the past, NHTSA has addressed the need to remove, disconnect, or otherwise alter mandatory safety equipment for people with disabilities by issuing, in certain circumstances, a separate letter assuring the individual requestor that we will not take enforcement action against the business modifying the vehicle. However, on February 27, 2001 a final rule creating limited exceptions to the "make inoperative" provision was published in the Federal Register (66 FR 12638). These limited exceptions allow repair businesses to modify certain types of Federally-required safety equipment and features, under specified circumstances.

One of the general concerns raised by your letter is how the wide range of positions that the seat may be adjusted to, if the PTSB is used, may affect compliance with safety standards. There is no Federal motor vehicle safety standard that limits or specifies the location or range of adjustment in a seat. However, you correctly observe that modifying an existing OEM seat to provide a range of adjustments that allow an occupant to be located outside of the range of locations allowed by the OEM seat could affect compliance with a number of standards, including Standard No. 208, Occupant crash protection, Standard No. 210, Seat belt assembly anchorages, and Standard No. 207, Seating systems. Any modifier who installed the PTSB prior to first sale would have to assure that the vehicle continued to meet these safety standards and certify that the vehicle complied before the vehicle could be sold. If the PTSB were to be installed after the vehicle had been sold to a consumer, a professional repair shop or installer would have to avoid violating the "make inoperative" provisions outlined above. If determining whether the installation would make a required safety feature inoperative would be prohibitively expensive or difficult, the installer could apply to NHTSA for an exemption from the "make inoperative" provision.

Your letter also contains a number of individual questions regarding Standards No. 207 and No. 210. These questions and the agency's response are provided below:

Question 1. What is a seat pedestal?

Response: The term "seat pedestal" is not defined in Standard No. 207 or Standard No. 210. NHTSA considers a "seat pedestal" to be a columnar structure on the lower portion of a seat used to attach the remainder of the seat to a vehicle. Seat pedestal seat are often used in heavy trucks and buses where an air suspension system is incorporated into the seat. NHTSA considers seat pedestals to be part of the seat itself for the purposes of Standard No. 207.

Question 2. What components are considered part of the seat pedestal?

Response: As noted above, for the purposes of Standards No. 207 the seat pedestal is considered to be part of the seat. Under Standard No. 210, a pedestal may also be a seat belt anchorage. The fact that a pedestal may be a seat belt anchorage under Standard No. 210 does not prevent the same component from being part of a seat under Standard No. 207.

Question 3. Is a seat pedestal the same as a seat base?

Response: Yes.

Question 4. Where is the dividing line between the seat and seat pedestal?

Response: For the purposes of Standard No. 207 and No. 210, there is no dividing line.

Question 5. Are the manual sliding adjustment tracks on the bottom of a seat part of the seat or part of the seat pedestal? Are these manual sliding adjustment tracks part of the seat, since the tracks are unboltable from the seat pedestal and not from the seat?

Response: Sliding adjustment tracks on the bottom of a seat are part of the seat. As any pedestal is considered part of the seat, the manner in which the adjustment tracks are attached or incorporated into the seat has no bearing on whether the tracks are part of the seat.

Question 6. Is the power adjusting mechanism part of the seat or the seat pedestal? Is this power adjusting mechanism part of the seat, since the power mechanism is unboltable from the seat pedestal and not from the seat?

Response: If a power adjustment mechanism is provided, it is part of the seat. As noted above, the manner in which a pedestal is attached to an adjustment mechanism is immaterial, as the pedestal is considered part of the seat.

Question 7. Is the seat considered to be anything that is unboltable from the seat pedestal?

Response: No.

Question 8. Refer to FMVSS 207, Section 3, Definitions. "Seat adjuster means the part of the seat that provides forward and rearward positioning of the seat bench and back, and /or rotation around a vertical axis, including any fixed portion, such as a seat track. In the case of a seat equipped with seat adjusters at different levels, the term means the uppermost seat adjuster." These 2 statements pose the following questions:

a.) With respect to statement #1 in bold quotations above, is a PTSB considered part of the seat?

Response: Yes.

b.) If the PTSB is considered part of the seat, why is the term "seat pedestal" included in FMVSS 210, Section 3, Definitions, if there is no "seat pedestal" due to FMVSS 207, Section 3, definitions?

Response: Standard No. 210 applies to seat belt assembly anchorages, including anchorages that are incorporated into seats. The term seat pedestal was included in the definition of "seat belt anchorage" contained in Standard No. 210 to ensure that readers of the standard understood that a seat pedestal could also serve as a seat belt anchorage.

c.) With respect to statement #2 in bold quotations above, the PTSB has 2 seat adjusters at 2 different levels. The uppermost seat adjuster is specified only here. To perform the FMVSS 207 and FMVSS 210 testing, where does the lower seat adjuster need to positioned?

Response: The performance requirements in S4.2 of Standard No. 207 specify the amount of force the seat must withstand when tested in accordance with S5 of the standard. According to S5, "Test Procedures," for a seat whose back and seat bench are attached to the vehicle with the same attachment and whose height is adjustable, the loads are applied when the seat is in its highest adjustment position. With respect to the PTSB and the conditions specified in page 9 of this letter, we recommend that the forces specified in S4.2(a) and S4.2(b) be applied with the OEM seat at its highest original position.

Question 9. Refer to FMVSS 207, S4.2, General Performance Requirements. Sentence number one states, "When tested in accordance with S5., each occupant seat, other than....". Does this term "occupant seat" refer to just the seat or the seat and pedestal combined?

Response: As noted above, the term occupant seat refers to the seat and the pedestal combined.

Question 10. Refer to FMVSS 207, Section 4.2.1., Seat Adjustment. The first statement states, "Except for vertical movement of nonlocking suspension type occupant seats in trucks and buses, each seat shall remain in its adjusted position when tested in accordance with the test procedures specified in S5." Does this above statement mean the "nonlocking suspension portion" of this suspension type occupant seat is actually considered part of seat and not the seat pedestal? Can a seat pedestal have a nonlocking suspension?

Response: The nonlocking suspension portion of a seat is considered part of the seat. As noted above, a seat pedestal is considered to be part of a seat. A seat pedestal may have a nonlocking suspension only when it is installed either in a truck or a bus. This would preclude the installation of a seat with a nonlocking suspension in an MPV or passenger car.

Question 11. Refer to FMVSS 210, Section 3, Definition. "Seat Pedestal" is listed but no definition is given as to what, specifically, is a seat pedestal. Refer to Question #1 above and give a definition.

Response: See the response to question 1.

Question 12. Refer to FMVSS 210, Section 4.3.1.1(a) and 4.3.1.1(b). "If the seat is a nonadjustable seat (for part a), or if the seat is an adjustable seat (for part b), then a line...". Are these sentences referring just to the seat or the seat and seat pedestal combined? If the sentences are referring to the seat and seat pedestal combined, our PTSB positions the seat at the center of the vehicle where it is not driveable.

Response: Question 12 Sections 4.3.1.1(a) and 4.3.1.1(b) specify the allowable range of belt angles resulting from the location of seat belt anchorages within a vehicle. As any pedestal is part of the seat, the use of the term "seat" in these sections refers to any pedestal and seat as a single assembly. The determination of these angles is based on measurements taken from the Seating Reference Point (SgRP) - which is defined, in part, in S571.3 - as the rearmost normal driving position. By definition, these belt angles are determined with the seat in its rearmost driving position, not necessarily the rearmost position that seat can attain. However, under most circumstances, these positions would be the same.

Question 13. Refer to FMVSS 210, Section 4.3.1.2, the end on the first sentence. "...on the seat frame with the seat in the rearmost position". Is this referring to just the seat or the seat and seat pedestal combined? If this is referring to the seat and seat pedestal combined, the same situation occurs as with question #12 above.

Response: As noted above, the seat pedestal is considered to be part of the seat itself. Again, the Seating Reference Point (SgRP) is the point that is used as a reference point in determining belt angles.

Question 14. Refer to FMVSS 210, Section 4.3.2, the second sentence. "Adjust the seat to its full rearward and downward position...." Is this referring to just the seat or seat and the seat pedestal combined? If this is referring to the seat and the seat pedestal combined, the same situation occurs as with question #12 above.

Response: Again, the seat pedestal is part of the seat assembly.

Question 15. Refer to FMVSS 210, Section 4.3.2(b). "For adjustable anchorages, compliance with this section shall be determined at the midpoint of the range of all adjustment positions." The female seat belt receptacle is located on the OEM seat or the OEM seat pedestal. Since there is now a PTSB installed in the vehicle, the female seat belt receptacle is moveable with the PTSB. Does the above bold quotation mean the range of all adjustment locations of the PTSB? Or, since the female seat belt receptacle is not adjustable, is the above bold quotation not relevant to the female seat belt receptacle?

Response: S4.3.2(b) addresses the permissible range of locations for upper anchorages of Type 2 belts and specifies that any adjustable anchorage shall be located at the midpoint of any adjustment positions when the location of the upper anchorage is tested for compliance with Standard No. 207. Unless the female receptacle is located on an upper anchorage, S4.3.2 does not apply.

Question 16.

Refer to FMVSS 210, Section 5.2, Seats with Type 2 or Automatic Seat Belt Anchorages. First sentence. "With the seat in its rearmost position, apply..." Is this statement referring to just the seat or seat and seat pedestal combined? If this is referring to the seat and seat pedestal combined, the same situation occurs with question #12 above.

Response: As noted above, NHTSA considers the seat pedestal to be part of the seat. S5.2 outlines the performance requirements for belt anchorages. S5.2, which does not distinguish between driver and passenger seats, specifies that a seat must be in its rearmost position when the anchorages are tested. Accordingly, NHTSA would test the anchorages in that rearmost position, even in the event the rearmost position would not allow most drivers to actually operate the vehicle.

Question 17. In the FMVSS 207 & FMVSS 210 standards, the vertical positioning of the OEM seat adjuster is specified. If an up/down travel mechanism is installed above the swivel mechanism, but below the OEM seat, where does this up/down travel mechanism need to be positioned for the FMVSS 207 & FMVSS 210 testing?

Response: The general performance requirements for seats are found in S4.2 of Standard No. 207. S4.2(a) and S4.2(b), which specify the forces that a seat must withstand in the forward and rearward directions, both specify that the seat is tested in any position to which the seat can be adjusted. S4.2(d) specifies that a seat is in its rearmost adjustment position. The agency has consistently interpreted these sections to require that a seat meet these requirements at any vertical position within the seat's range of adjustment.

You also ask, in light of the ability of the PTSB and the OEM adjuster to move a seat over a wide range, where do the PTSB, the OEM seat and all adjuster mechanisms need to be positioned to conduct static pull tests under Standard No. 207 and Standard No. 210? I assume that your inquiry regarding static pull tests relates to meeting the requirements of S4.2 of Standard No. 207 and S4.2 of Standard No. 210, and performing the anchorage strength test procedure found in S5.1 and S5.2 of Standard No. 210. S5.1 and S5.2 both specify that a seat is in the rearmost position when the test is performed. If a seat is adjusted in its rearmost position and its relative fore and aft position does not change when moved through the range of vertical adjustments, a compliance test may be performed at any vertical position of adjustment. If the vertical movement of the seat moves the seat in such a fashion that the fore and aft position of the seat changes during the vertical movement, the seat would be tested in the rearmost position as attained by the use of both the vertical and horizontal adjustments.

Finally, you make a number of suggestions for either amending or clarifying Standards No. 207 and No. 210. One suggestion you make is that the agency create different definitions of "primary" and "secondary" seat adjusters. You suggest that an adjuster that is closest to the seat structure, presumably the seat pan, should be defined as the "primary" adjuster and the "secondary" adjuster should be an adjuster furthest from the seat pan or an adjuster that has the ability, like the PTSB, to move individuals beyond the "seatbelt" and "airbag" zones. In your view, Standards No. 207, No. 210, and No. 208 should be amended or interpreted to specify that existing requirements relating to seat adjustments should apply to the "primary" adjuster only and that any and all secondary adjusters should be adjusted to their maximum downward position with the seat facing forward and aligned with the centerline of the steering wheel. Depending on the standard involved, the secondary adjuster should be adjusted to its maximum forward position or its maximum rearward position as appropriate. Alternatively, you suggest that the definitions in Standard No. 207 and No. 210 be modified so that a seating system would consist of three components. The first component would be the seat itself, including all structures above the adjuster assembly. The second component would be the pedestal, which would be any component between the adjustment mechanism and the vehicle structure. The third component would be the adjuster, which would be that portion of the seating system that provides any movement of the seat.

I would like to emphasize that NHTSA is very concerned about the safety of all motor vehicles users, including those with disabilities. At the same time, the agency is also very much aware that there is growing need for adaptive vehicles that provide mobility for persons with special needs. As noted above, NHTSA has just issued a final rule that provides limited exemptions to the "make inoperative" provisions of Chapter 301 when a vehicle must be modified for a particular individual (66 FR 12638). However, this final rule does not contain any exemptions from Standard No. 207 or Standard No. 210 allowing for the installation of six-way power seat bases similar to the PTSB. The agency stated in the notice of proposed rulemaking (NPRM) preceding the final rule that in the case of six-way power seat bases, it was reasonable and practicable to expect that such seat bases could be manufactured to comply with Standard No. 207 (63 FR 51557). Similarly, NHTSA also believed that there was no need to create an exemption for Standard No. 210 (63 FR 51558). None of the comments submitted in response to the NPRM took issue with the agency's position regarding either of these standards. Accordingly, the final rule did not provide an exemption either for six-way power seat bases or for Standard No. 210. However, in considering the case of six-way power seat bases, NHTSA did not distinguish between the positions the seats may attain when being used for ingress and egress and those positions the seats may be used in when the vehicle is capable of being driven.

In regard to your suggestions relating to modifying the definitions in Standard No. 207 and Standard No. 210 to create a distinction between "primary" and "secondary" adjusters or the seat "pedestal" and the "adjuster" or base, doing so would require that NHTSA amend these standards through rulemaking. Moreover, redefining a device such as the PTSB as a "secondary adjuster" or a "pedestal," without taking into account the ability of the device to adjust the seat when the vehicle is being used on the highway, would ignore the potential safety consequences of its use as well as the fact that the PTSB and similar devices, when installed, are the sole means by which the seat is attached to the vehicle. Therefore, we decline to adopt any interpretation that would create such a definition.

Standard No. 207 is intended to ensure that seats and their attachments are strong enough not to fail as a result of "forces acting on them as a result of vehicle impact." (S1) In light of your letter, the agency has examined the need for adaptive vehicles to accommodate persons with disabilities. We note that your product works in conjunction with an OEM seat to assist individuals in entering and exiting the vehicle. If the PTSB does not provide an additional range of adjustments beyond those provided by the OEM seat while the vehicle is in motion, the purposes of Standard No. 207 would be met by testing the PTSB within the range of the OEM adjustments. Accordingly, NHTSA would exercise its enforcement discretion and refrain from taking action in the event a vehicle equipped with such a PTSB is found not to comply with Standards No. 207 and No. 210. However, this exercise of our enforcement discretion would be limited to those instances where the following conditions are met:

1) The PTSB or a similar device cannot be operated while the vehicle is in motion.

2) The PTSB must return the OEM seat to a position within the range of adjustments of the OEM seat as originally installed before the vehicle can move under its own power.

3) The seat of a PTSB equipped vehicle cannot be moved outside of the range of adjustment attainable by the OEM seat originally provided with the vehicle while the vehicle is in motion.

4) Certification tests establish that PTSB equipped vehicles meet the requirements of all applicable standards with the PTSB positioned as it would be while the vehicle is in motion - i.e., within the range of adjustments of the seat as installed by the original manufacturer of the vehicle.

I hope this information answers your questions. Please contact Otto Matheke of my office at (202) 366-5253 if you have further questions.

Sincerely,

John Womack
Acting Chief Counsel

ref:207
d.8/21/01

ID: 6992

Stephen E. Selander, Esq.
Legal Staff
General Motors Corporation
New Center One Building
3031 West Grand Boulevard
P.O. Box 33122
Detroit, MI 48232

Dear Mr. Selander:

This responds to your February 17, 1992 request for interpretations of Federal Motor Vehicle Safety Standards No. 101, Controls and Displays and No. 105, Hydraulic Brake Systems, as those standards would apply to an electric vehicle (GMEV) that General Motors (GM) is preparing to sell in the future. You requested the agency's concurrence with, or guidance regarding, nine proposed interpretations. Your questions are addressed below.

Before discussing the substantive issues that you raised, I note that you requested confidential treatment for portions of certain materials that you provided relating to the brake system planned for the electric vehicle. These materials were previously submitted to NHTSA, and the agency granted confidentiality for portions of the materials in letters dated July 18, 1991 and August 12, 1991. In a letter accompanying your request for interpretation, GM released from its request for confidential treatment portions of the materials for which confidentiality had previously been granted. NHTSA's earlier grants of confidentiality remain in effect for the remaining portions for which GM continues to seek confidential treatment. Accordingly, this letter does not cite any of the confidential information.

I also note that, in one of the attachments to your letter, you suggested several amendments to Standard No. 105 that you believe would facilitate the introduction of electric vehicles. As you know, NHTSA recently issued an advance notice of proposed rulemaking (ANPRM) to solicit comments to help the agency determine what existing standards may need modification to meet the needs associated with the introduction of electric vehicles and what new standards may have to be written specifically for electric vehicles. See 56 FR 67038, December 27, 1991. We will consider your recommendations concerning Standard No. 105 as we evaluate the comments on the ANPRM. The scope of this letter is limited to addressing how the current requirements of Standards No. 101 and No. 105 would apply to your planned vehicle.

By way of background information, NHTSA does not provide approvals of motor vehicles or motor vehicle equipment. Under the National Traffic and Motor Vehicle Safety Act, it is the responsibility of the manufacturer to ensure that its vehicles and equipment comply with applicable requirements. The following represents our opinion based on the facts provided in your letter.

Standard No. 101; Controls and Displays

GM Proposed Interpretation 1: Permit electrically powered vehicles to use symbols that are appropriate for indicating electric power reserve.

You asked two questions regarding how Standard No. 101 would apply to the GM electric vehicle. The first question concerned the identification for a gauge that would monitor battery charge as a percent of full charge. This gauge would serve as the functional equivalent of a fuel gauge in traditional internal combustion engine (ICE) vehicles. You stated, however that it would be inappropriate and potentially misleading to use Standard No. 101's fuel symbol (a picture of a gasoline pump) for a gauge indicating electric power reserve. You stated that you planned to identify the gauge with the ISO battery symbol (a picture of a battery), which you indicated is substantially similar to that found in Standard No. 101 for electrical charge. You requested NHTSA's concurrence that electric vehicles are permitted to use symbols that are appropriate for identifying electric power reserve and not the Standard No. 101 fuel symbol.

Standard No. 101 requires that new vehicles with any display listed in the standard must meet specified requirements for the location, identification and illumination of such display. See S5(a). Thus, the primary issue raised by your question is whether a gauge indicating electric power reserve is among the displays listed in the standard, and if so, what identification requirements apply.

As you noted in your letter, one of the displays listed in Standard No. 101 is a fuel gauge. See S5.1 and Table 2. The dictionary defines "fuel" as combustible matter used to maintain fire, as coal, wood, oil, etc. See Random House Dictionary of the English Language (unabridged edition). Electrical power provided by a battery does not come within the meaning of "fuel." Therefore, a gauge indicating electric power reserve for an electric vehicle is not a fuel gauge.

Another display listed in Standard No. 101 is an electrical charge gauge. This term refers to gauges that indicate whether, and the extent to which, a vehicle's battery is charging. Therefore, a gauge indicating electric power reserve for an electric vehicle is not an electric charge gauge within the meaning of Standard No. 101.

Since a gauge indicating electric power reserve is not otherwise covered by Standard No. 101 or any other standard, its identification is at the option of the manufacturer.

GM Proposed Interpretation 2: Allow the "Service Soon" telltale to indicate loss of powertrain oil pressure for the GMEV.

Your second question concerned whether low oil pressure may be indicated by activation of a "Service Soon" telltale instead of one identified by Standard No. 101's oil pressure symbol (a picture of an oil can) or the word "oil." You stated that a "Service Soon" telltale would be more appropriate for an electric vehicle, since it (unlike ICE vehicles) can continue to be driven without oil pressure.

One of the displays listed in Standard No. 101 is an oil pressure telltale. While the seriousness of low oil pressure may be different for electric vehicles than ICE vehicles, the condition for activation of an oil pressure telltale (low oil pressure) would be the same. It is our opinion that Standard No. 101's identification requirements would apply to an oil pressure telltale for an electric vehicle. If a manufacturer is concerned that the oil pressure symbol or the word "oil" might be misleading to drivers familiar with ICE vehicles, the manufacturer is free to provide additional words or symbols for the purpose of clarity. See S5.2.3.

It is not clear, however, that the telltale you plan would be considered a low oil pressure telltale within the meaning of Standard No. 101. You state that, as currently planned, the electric vehicle will be equipped with a "Service Soon" telltale which will light in the event of a malfunction that could eventually cause damage to the vehicle powertrain, but does not require immediate attention. It thus appears that the telltale might monitor several possible vehicle conditions, one of which is low oil pressure. Standard No. 101 does not require that any of the displays listed in the standard be provided or that two or more displays, if provided, be provided separately. NHTSA has previously concluded that a multipurpose telltale which monitors two functions, oil pressure and coolant temperature, may be identified by the word "Engine." See December 29, 1978 letter to Ford Motor Company. The basis for this interpretation was that while Standard No. 101 specifies requirements for oil pressure and coolant temperature telltales, it does not specify any requirements for a single telltale which covers both conditions. For the same reason, if GM provided a single telltale monitoring several vehicle conditions, one of which was low oil pressure, the standard's requirements for an oil pressure telltale would not apply and the identification for that telltale would be at the discretion of the manufacturer.

Standard No. 105; Hydraulic Brake Systems

You asked seven questions regarding how Standard No. 105 would apply to the GM electric vehicle. You provided the following general description of the brake system planned for the vehicle:

The brake system consists of front hydraulic disc (service) brakes, rear electric drum (service and parking) brakes, four-wheel ABS, and regenerative braking. Brake pedal forces and travel are comparable to conventional power assisted hydraulic brake systems, and are independent of the state-of-charge of the vehicle's battery pack. The design features a manual hydraulic "push through" to apply the front brakes in the event of any electrical failure.

Standard No. 105 applies to passenger cars and various other vehicle types with "hydraulic service brake systems." See S3. Since the service brakes of the GM electric vehicle would be partly hydraulic brakes and partly electric brakes, a preliminary issue is whether the standard would apply to the vehicle. As discussed below, it is our opinion that the standard would apply to the vehicle.

The term "hydraulic brake system" is defined in S4 as "a system that uses hydraulic fluid as a medium for transmitting force from a service brake control to the service brake, and that may incorporate a brake power assist unit, or a brake power unit." The term "service brake" is defined at Part 571.3 as "the primary mechanism designed to stop a motor vehicle."

The planned braking system would use hydraulic fluid as a medium for transmitting force from the service brake control to the front brake portion of the service brake. It is our interpretation that this is sufficient, under the definition of "hydraulic brake system," for the braking system to be considered a "hydraulic brake system," even though hydraulic fluid is not used for the rear brake portion of the service brake. Therefore, Standard No. 105 would apply to the vehicle.

GM Proposed Interpretation 3: The GMEV parking brake is mechanically retained in accordance with the requirements of S5.2.

Your first question on Standard No. 105 concerned S5.2's requirement that vehicles be manufactured "with a parking brake system of a friction type with a solely mechanical means to retain engagement." You stated that the parking brake on the GMEV would be applied and released by electrical means, but would be retained by a mechanical latching device. You requested NHTSA's concurrence that the planned parking brake would satisfy the requirement for mechanically retained engagement. We agree that S5.2 permits the parking brake to be applied and released by electrical or other non-mechanical means, so long as engagement is held by solely mechanical means.

Your next several questions concern Standard No. 105's brake failure requirements. As noted by your letter, these requirements are set forth in S5.1.2 (partial failure), S5.1.3 (inoperative brake power assist unit or brake power unit), and S5.5 (failure in antilock or variable proportioning brake system), and the test procedures for these requirements are set forth in S7.9 and S7.10.

GM Proposed Interpretation 4: The subject brake system is a "split service brake system" consisting of four subsystems-- one at each wheel.

Standard No. 105 specifies different partial failure requirements depending on whether a vehicle is manufactured with a split service brake system. The term "split service brake system" is defined in S4 as "a brake system consisting of two or more subsystems actuated by a single control designed so that a leakage-type failure of a pressure component in a single subsystem (except structural failure of a housing that is common to two or more subsystems) shall not impair the operation of any other subsystem."

We agree that your planned vehicle can be viewed as having four subsystems, one at each wheel. In only two of the subsystems, however, can leakage-type failures occur (the two hydraulic subsystems). Thus, in determining whether the vehicle has a split service brake system within the meaning of Standard No. 105, the key is whether a leakage-type failure of a pressure component in either of those two subsystems (except structural failure of a housing that is common to two or more subsystems) impairs the operation of any other subsystem (i.e., the other hydraulic subsystem or either of the two other subsystems). After reviewing the information provided with your letter, we have no reason to doubt that your planned system qualifies as a split service brake system.

GM Proposed Interpretation 5: The four service brake subsystems may be certified to the requirements of S5.1.2 in accordance with the test procedure of S7.9.1 through S7.9.3 by disabling each subsystem in a way that does not affect the other three subsystems.

Standard No. 105's requirements for partial failure are set forth in S5.1.2. For vehicles with a split service brake system, 5.1.2.1 provides that, in the event of a rupture or leakage type of failure in a single subsystem, other than a structural failure of a housing that is common to two or more subsystems, the remaining portion(s) of the service brake system shall continue to operate and shall be capable of stopping a vehicle from 60 mph within specified stopping distances. You suggested that certification of the requirements of S5.1.2.1, consistent with the procedure of S7.9.1 through S7.9.3, should be established by disabling each of the four subsystems in turn. You also stated that, for purposes of compliance testing, the subsystems would be disabled in such a way that the functioning of only one subsystem would be affected.

It is our opinion that, in testing under S5.1.2.1, only the two hydraulic subsystems of your planned brake system would be disabled, as S5.1.2.1 only addresses rupture/leakage types of failures. It does not address any type of failure of a subsystem for which a rupture or leakage type failure cannot occur. We would not consider a break in an electrical system to be a "rupture" within the meaning of Standard No. 105.

We are uncertain as to the meaning of your statement that, for purposes of compliance testing, the subsystems would be disabled in such a way that the functioning of only one subsystem would be affected. This could be read as meaning that the agency must induce a rupture or leakage type failure in a place that doesn't affect other subsystems. However, under S7.9.1, any one rupture or leakage type of failure is introduced, other than a structural failure of a housing that is common to two or more subsystems. If any such leakage type failure impaired another subsystem, the brake system would not, of course, be considered a split service brake system within the meaning of Standard No. 105.

GM Proposed Interpretation 6: The GMEV brake system may be certified to the requirements of S5.1.3 in accordance with the test procedure of S7.10 by functionally disabling the BCU. Such a procedure will completely disable the brake power assist, and since the electric motors within the hydraulic unit and the rear brake drums are separately disabled during S5.1.2 testing, there is no need to separately consider these electric motors when certifying to the requirements of S5.1.3.

Standard No. 105's requirements for inoperative brake power assist unit or brake power unit are set forth in S5.1.3. You stated that your planned brake system would not utilize conventional power assist, but brake power assist would be provided by the combination of the BCU and four electric motors. You stated that this design does not lend itself to an obvious way of distinguishing brake power assist from other service brake subsystem components, and suggested that the brake system be certified to the requirements of S5.1.3 by disabling the BCU (which would disable all four electric motors and completely eliminate functional brake power assist) and then satisfying the provisions of either S5.1.3.1, S5.1.3.2, or S5.1.3.4. You also sought the agency's concurrence that there is no need to otherwise take the four electric motors into account when certifying to the requirements of S5.1.3.

S4 of Standard No. 105 defines the term "brake power assist unit" as a device installed in a hydraulic brake system that reduces the operator effort to actuate the system, and that if inoperative does not prevent the operator from braking the vehicle by a continued application of muscular force on the service brake control. Under the options of S5.1.3.1, S5.1.3.2, and S5.1.3.4, stopping distance requirements must be met with one brake power assist unit inoperative.

We believe that each electric motor comes within the definition of "brake power assist unit." In addition, given the integrated nature of the BCU and the four electric motors, we believe that the combination of the BCU/four electric motors also comes within the definition of "brake power assist unit." It is therefore our opinion that the requirements of S5.1.3 must be met both when the BCU is disabled (which would disable all four electric motors and completely eliminate functional brake power assist) and also when each of the four electric motors is disabled individually.

We note that, under our interpretation of S5.1.2 discussed above, not all of the four electric motors are separately disabled during S5.1.2 testing.

GM Proposed Interpretation 7: The GMEV brake system may be certified to the requirements of S5.5 in accordance with the test procedure of S7.9.4 by functionally disabling the BCU. Since such a procedure will completely disable ABS and the variable proportioning function, no other testing is required in connection with S5.5.

Standard No.105's requirements for failed antilock and variable proportioning brake systems are set forth in S5.5. You stated that the BCU is the functional power source for the GMEV's ABS, and that the BCU also regulates the proportion of front to rear braking. You sought the agency's concurrence that disabling the BCU is the appropriate means of complying with S5.5, and is consistent with the procedure of S7.9.4.

S5.5 provides that a vehicle shall meet certain stopping distance requirements in the event of failure (structural or functional) in an antilock or variable proportioning brake system. S7.9.4 provides the following test procedure:

With vehicle at GVWR, disconnect functional power source, or otherwise render antilock system inoperative. Disconnect variable proportioning brake system. Make four stops, each from 60 mph. If more than one antilock or variable proportioning brake subsystem is provided, disconnect or render one subsystem inoperative and run as above. Restore system to normal at completion of this test. Repeat for each subsystem provided.

We concur that your planned brake system should be tested to the requirements of S5.5 in accordance with the test procedure of S7.9.4 by functionally disabling the BCU, and that no other testing is required. Under S7.9.4, the antilock system is to be rendered inoperative and the variable proportioning system is to be disconnected. Both of these procedures are accomplished by functionally disabling the BCU. Further, it is our opinion that the planned brake system would not have antilock or variable proportioning subsystems, since antilock at all four wheels and variable proportioning are all controlled by the BCU.

GM Proposed Interpretation 8: Assuming the conditions established in proposed S6.2, regenerative braking is permitted to function normally when conducting the test procedures of S7. In particular, the phrase "service brakes shall be capable of stopping" (found in S5.1.4 and S5.1.5, for example) is not to be construed as prohibiting the normal operation for regenerative braking.

In addressing how the current requirements of Standard No. 105 would apply to your vehicle, we cannot assume the conditions you recommend establishing in a new S6.2. The agency would need to add those conditions to the standard in rulemaking. I will therefore address how regenerative braking would be treated under the current requirements.

As discussed in your letter, regenerative braking assists in decelerating the vehicle by converting the kinetic energy of the moving vehicle into stored electrical energy within the vehicle's battery pack. Regenerative braking on the planned GM electric vehicle will supplement, under certain conditions, the friction braking provided by the service brakes. You stated that regenerative braking will only be available when the vehicle is "in gear." Since the large majority of Standard No. 105 tests are conducted with the vehicle in "neutral," regenerative braking will have no influence on the outcome of those tests. You indicated that since some Standard No. 105 tests, notably fade and recovery and the water test, are conducted with the the vehicle "in gear," regenerative braking could occur during these tests.

You stated that you believe that regenerative braking should generally be allowed to function normally during Standard No. 105 testing. You argued that the regenerative braking which may occur during "in gear" Standard No. 105 tests is little different from the engine braking which occurs in conventional ICE vehicles. We agree that regenerative braking should function normally during Standard No. 105 testing, just as engine braking occurs normally during Standard No. 105's "in gear" tests.

Another issue that you raised in connection with regenerative braking is the state of battery charge during testing, which can affect the amount of regenerative braking. You proposed (for your recommended new S6.2) that tests be initiated with a full charge of the vehicle's battery pack, so that the amount of regenerative braking that would occur during the tests would be minimized to the least amount that could occur in real world driving, i.e., the tests would be conducted under "worst case" conditions.

While Standard No. 105 specifies many test conditions, it does not specify state-of-battery charge. In an interpretation letter to Mazda dated October 2, 1990, we provided general guidance concerning how NHTSA interprets a standard where it does not specify a particular test condition. First, we stated that, in the absence of a particular test condition, we believe there is a presumption that the requirements need to be met regardless of such test condition, since the standard does not include any language which specifically limits applicability of its requirements to such test condition. We also indicated, however, that before reaching such a conclusion, we also consider the language of the standard as a whole and its purposes.

It is our opinion that the braking requirements of Standard No. 105 must be met regardless of the state of battery charge. The purpose of Standard No. 105 is to ensure safe braking performance under normal and emergency conditions. Since an electric vehicle will be driven with the battery at various states of charge, safe braking performance can only be ensured if the standard's requirements can be met in all such conditions. This would generally be consistent with GM's suggestion that compliance testing be conducted under "worst case" conditions.

GM Proposed Interpretation 9: In addition to the explicit conditions for activation of the brake telltale set forth in S5.3 of the standard, permit illumination of the service brake telltale when an impending or latent brake system malfunction is detected during electrical diagnosis.

As noted by your letter, S5.3.1 of Standard No. 105 requires a brake telltale to illuminate when there is a gross loss of hydraulic pressure (or, alternatively, a drop in fluid level), a total functional electrical failure in the antilock or variable proportioning brake system, and when the parking brake is applied. You stated that a brake telltale on the planned GMEV would illuminate under these prescribed conditions. You indicated, however, that a diagnostic capability will also exist to detect other faults in the brake system, and requested the agency's concurrence that S5.3.1 permits illumination of the brake telltale when other faults are detected which increase the likelihood of a substantial degradation in brake system performance.

While Standard No. 105 requires that a brake telltale be provided which activates under certain specified conditions, it does not expressly state whether the required telltale may also be activated under other conditions. It is our opinion that the telltale may also activate under other conditions so long as such activation does not obscure or confuse the meaning of the required telltale or otherwise defeat its purpose. I note that this test is similar to one the agency has long used in addressing the issue of whether additional information may be provided along with information that is required to be labeled on certain products in the context of our safety standards. See, for example, NHTSA's December 20, 1991 interpretation letter to GM concerning Standard No. 209.

The purpose of the brake telltale is to warn the driver of one of two conditions: (1) the parking brake is applied (and hence should be released before driving), or (2) the brake system has a significant fault which should be corrected. Since the additional conditions for activation which GM contemplates would represent significant brake system faults which should be corrected, it is our opinion that activation of the brake telltale under such conditions would not in any way defeat the purpose of the brake telltale.

I hope you find this information helpful. If you have further questions, please contact Edward Glancy of my staff at this address or by telephone at (202) 366-2992.

Sincerely,

Paul Jackson Rice Chief Counsel ref:101#105 d:4/29/02

ID: nht92-7.23

DATE: April 29, 1992

FROM: Paul Jackson Rice -- Chief Counsel, NHTSA

TO: Stephen E. Selander -- Legal Staff, GM

TITLE: None

ATTACHMT: Attached to letter dated 2/17/92 from Stephen E. Selander to Paul Jackson Rice

TEXT:

This responds to your February 17, 1992 request for interpretations of Federal Motor Vehicle Safety Standards No. 101, Controls and Displays and No. 105, Hydraulic Brake Systems, as those standards would apply to an electric vehicle (GMEV) that General Motors (GM) is preparing to sell in the future. You requested the agency's concurrence with, or guidance regarding, nine proposed interpretations. Your questions are addressed below.

Before discussing the substantive issues that you raised, I note that you requested confidential treatment for portions of certain materials that you provided relating to the brake system planned for the electric vehicle. These materials were previously submitted to NHTSA, and the agency granted confidentiality for portions of the materials in letters dated July 18, 1991 and August 12, 1991. In a letter accompanying your request for interpretation, GM released from its request for confidential treatment portions of the materials for which confidentiality had previously been granted. NHTSA's earlier grants of confidentiality remain in effect for the remaining portions for which GM continues to seek confidential treatment. Accordingly, this letter does not cite any of the confidential information.

I also note that, in one of the attachments to your letter, you suggested several amendments to Standard No. 105 that you believe would facilitate the introduction of electric vehicles. As you know, NHTSA recently issued an advance notice of proposed rulemaking (ANPRM) to solicit comments to help the agency determine what existing standards may need modification to meet the needs associated with the introduction of electric vehicles and what new standards may have to be written specifically for electric vehicles. See 56 FR 67038, December 27, 1991. We will consider your recommendations concerning Standard No. 105 as we evaluate the comments on the ANPRM. The scope of this letter is limited to addressing how the current requirements of Standards No. 101 and No. 105 would apply to your planned vehicle.

By way of background information, NHTSA does not provide approvals of motor vehicles or motor vehicle equipment. Under the National Traffic and Motor Vehicle Safety Act, it is the responsibility of the manufacturer to ensure that vehicles and equipment comply with applicable requirements. The following represents our opinion based on the facts provided in your letter.

STANDARD NO. 101; CONTROLS AND DISPLAYS

GM PROPOSED INTERPRETATIONS 1: PERMIT ELECTRICALLY POWERED VEHICLES TO USE SYMBOLS THAT ARE APPROPRIATE FOR INDICATING ELECTRIC POWER RESERVE.

You asked two questions regarding how Standard No. 101 would apply to the GM electric vehicle. The first question concerned the identification for a gauge that would monitor battery charge as a percent of full charge. This gauge would serve as the functional equivalent of a fuel gauge in traditional internal combustion engine (ICE) vehicles. You stated, however that it would be inappropriate and potentially misleading to use Standard No. 101's fuel symbol (a picture of a gasoline pump) for a gauge indicating electric power reserve. You stated that you planned to identify the gauge with the ISO battery symbol (a picture of a battery), which you indicated is substantially similar to that found in Standard No. 101 for electrical charge. You requested NHTSA's concurrence that electric vehicles are permitted to use symbols that are appropriate for identifying electric power reserve and not the Standard No. 101 fuel symbol.

Standard No. 101 requires that new vehicles with any display listed in the standard must meet specified requirements for the location, identification and illumination of such display. See S5(a). Thus, the primary issue raised by your question is whether a gauge indicating electric power reserve is among the displays listed in the standard, and if so, what identification requirements apply.

As you noted in your letter, one of the displays listed in Standard No. 101 is a fuel gauge. See S5.1 and Table 2. The dictionary defines "fuel" as combustible matter used to maintain fire, as coal, wood, oil, etc. See Random House Dictionary of the English Language (unabridged edition). Electrical power provided by a battery does not come within the meaning of "fuel." Therefore, a gauge indicating electric power reserve for an electric vehicle is not a fuel gauge.

Another display listed in Standard No. 101 is an electrical charge gauge. This term refers to gauges that indicate whether, and the extent to which, a vehicle's battery is charging. Therefore, a gauge indicating electric power reserve for an electric vehicle is not an electric charge gauge within the meaning of Standard No. 101.

Since a gauge indicating electric power reserve is not otherwise covered by Standard No. 101 or any other standard, its identification is at the option of the manufacturer.

GM PROPOSED INTERPRETATION 2: ALLOW THE "SERVICE SOON" TELLTALE TO INDICATE LOSS OF POWERTRAIN OIL PRESSURE FOR THE GMEV.

Your second question concerned whether low oil pressure may be indicated by activation of a "Service Soon" telltale instead of one identified by Standard No. 101's oil pressure symbol (a picture of an oil can) or the word "oil." You stated that a "Service Soon" telltale would be more appropriate for an electric vehicle, since it (unlike ICE vehicles) can continue to be driven without oil pressure.

One of the displays listed in Standard No. 101 is an oil pressure telltale. While the seriousness of low oil pressure may be different for electric vehicles than ICE vehicles, the condition for activation of an oil pressure telltale (low oil pressure) would be the same. It is our opinion that Standard

No. 101's identification requirements would apply to an oil pressure telltale for an electric vehicle. If a manufacturer is concerned that the oil pressure symbol or the word "oil" might be misleading to drivers familiar with ICE vehicles, the manufacturer is free to provide additional words or symbols for the purpose of clarity. See S5.2.3.

It is not clear, however, that the telltale you plan would be considered a low oil pressure telltale within the meaning of Standard No. 101. You state that, as currently planned, the electric vehicle will be equipped with a "Service Soon" telltale which will light in the event of a malfunction that could eventually cause damage to the vehicle powertrain, but does not require immediate attention. It thus appears that the telltale might monitor several possible vehicle conditions, one of which is low oil pressure.

Standard No. 101 does not require that any of the displays listed in the standard be provided or that two or more displays, if provided, be provided separately. NHTSA has previously concluded that a multipurpose telltale which monitors two functions, oil pressure and coolant temperature, may be identified by the word "Engine." See December 29, 1978 letter to Ford Motor Company. The basis for this interpretation was that while Standard No. 101 specifies requirements for oil pressure and coolant temperature telltales, it does not specify any requirements for a single telltale which covers both conditions. For the same reason, if GM provided a single telltale monitoring several vehicle conditions, one of which was low oil pressure, the standard's requirements for an oil pressure telltale would not apply and the identification for that telltale would be at the discretion of the manufacturer.

STANDARD NO. 105; HYDRAULIC BRAKE SYSTEMS

You asked seven questions regarding how Standard No. 105 would apply to the GM electric vehicle. You provided the following general description of the brake system planned for the vehicle:

The brake system consists of front hydraulic disc (service) brakes, rear electric drum (service and parking) brakes, four-wheel ABS, and regenerative braking. Brake pedal forces and travel are comparable to conventional power assisted hydraulic brake systems, and are independent of the state-of-charge of the vehicle's battery pack. The design features a manual hydraulic "push through" to apply the front brakes in the event of any electrical failure.

Standard No. 105 applies to passenger cars and various other vehicle types with "hydraulic service brake systems." See S3. Since the service brakes of the GM electric vehicle would be partly hydraulic brakes and partly electric brakes, a preliminary issue is whether the standard would apply to the vehicle. As discussed below, it is our opinion that the standard would apply to the vehicle.

The term "hydraulic brake system" is defined in S4 as "a system that uses hydraulic fluid as a medium for transmitting force from a service brake control to the service brake, and that may incorporate a brake power assist unit, or a brake power unit." The term "service brake" is defined at Part 571.3 as "the primary mechanism designed to stop a motor vehicle."

The planned braking system would use hydraulic fluid as a medium for transmitting force from the service brake control to the front brake portion of the service brake. It is our interpretation that this is sufficient, under the definition of "hydraulic brake system," for the braking system to be considered a "hydraulic brake system," even though hydraulic fluid is not used for the rear brake portion of the service brake. Therefore, Standard No. 105 would apply to the vehicle.

GM PROPOSED INTERPRETATION 3: THE GMEV PARKING BRAKE IS MECHANICALLY RETAINED IN ACCORDANCE WITH THE REQUIREMENTS OF S5.2.

Your first question on Standard No. 105 concerned S5.2's requirement that vehicles be manufactured "with a parking brake system of a friction type with a solely mechanical means to retain engagement." You stated that the parking brake on the GMEV would be applied and released by electrical means, but would be retained by a mechanical latching device. You requested NHTSA's concurrence that the planned parking brake would satisfy the requirement for mechanically retained engagement. We agree that S5.2 permits the parking brake to be applied and released by electrical or other non-mechanical means, so long as engagement is held by solely mechanical means.

Your next several questions concern Standard No. 105's brake failure requirements. As noted by your letter, these requirements are set forth in S5.1.2 (partial failure), S5.1.3 (inoperative brake power assist unit or brake power unit), and S5.5 (failure in antilock or variable proportioning brake system), and the test procedures for these requirements are set forth in S7.9 and S7.10.

GM PROPOSED INTERPRETATION 4: THE SUBJECT BRAKE SYSTEM IS A "SPLIT SERVICE BRAKE SYSTEM" CONSISTING OF FOUR SUBSYSTEMS -- ONE AT EACH WHEEL.

Standard No. 105 specifies different partial failure requirements depending on whether a vehicle is manufactured with a split service brake system. The term "split service brake system" is defined in S4 as "a brake system consisting of two or more subsystems actuated by a single control designed so that a leakage-type failure of a pressure component in a single subsystem (except structural failure of a housing that is common to two or more subsystems) shall not impair the operation of any other subsystem."

We agree that your planned vehicle can be viewed as having four subsystems, one at each wheel. In only two of the subsystems, however, can leakage-type failures occur (the two hydraulic subsystems). Thus, in determining whether the vehicle has a split service brake system within the meaning of Standard No. 105, the key is whether a leakage-type failure of a pressure component in either of those two subsystems (except structural failure of a housing that is common to two or more subsystems) impairs the operation of any other subsystem (i.e., the other hydraulic subsystem or either of the two other subsystems). After reviewing the information provided with your letter, we have no reason to doubt that your planned system qualifies as a split service brake system.

GM PROPOSED INTERPRETATION 5: THE FOUR SERVICE BRAKE SUBSYSTEMS MAY BE CERTIFIED TO THE REQUIREMENTS OF S5.1.2 IN ACCORDANCE WITH THE TEST PROCEDURE OF S7.9.1 THROUGH S7.9.3 BY DISABLING EACH SUBSYSTEM IN A WAY THAT DOES NOT AFFECT THE OTHER THREE SUBSYSTEMS.

Standard No. 105's requirements for partial failure are set forth in S5.1.2. For vehicles with a split service brake system, 5.1.2.1 provides that, in the event of a rupture or leakage type of failure in a single subsystem, other than a structural failure of a housing that is common to two or more subsystems, the remaining portion(s) of the service brake system shall continue to operate and shall be capable of stopping a vehicle from 60 mph within specified stopping distances. You suggested that certification of the requirements of S5.1.2.1, consistent with the procedure of S7.9.1 through S7.9.3, should be established by disabling each of the four subsystems in turn. You also stated that, for purposes of compliance testing, the subsystems would be disabled in such a way that the functioning of only one subsystem would be affected.

It is our opinion that, in testing under S5.1.2.1, only the two hydraulic subsystems of your planned brake system would be disabled, as S5.1.2.1 only addresses rupture/leakage types of failures. It does not address any type of failure of a subsystem for which a rupture or leakage type failure cannot occur. We would not consider a break in an electrical system to be a "rupture" within the meaning of Standard No. 105.

We are uncertain as to the meaning of your statement that, for purposes of compliance testing, the subsystems would be disabled in such a way that the functioning of only one subsystem would be affected. This could be read as meaning that the agency must induce a rupture or leakage type failure in a place that doesn't affect other subsystems. However, under S7.9.1, any one rupture or leakage type of failure is introduced, other than a structural failure of a housing that is common to two or more subsystems. If any such leakage type failure impaired another subsystem, the brake system would not, of course, be considered a split service brake system within the meaning of Standard No. 105.

GM PROPOSED INTERPRETATION 6: THE GMEV BRAKE SYSTEM MAY BE CERTIFIED TO THE REQUIREMENTS OF S5.1.3 IN ACCORDANCE WITH THE TEST PROCEDURE OF S7.10 BY FUNCTIONALLY DISABLING THE BCU. SUCH A PROCEDURE WILL COMPLETELY DISABLE THE BRAKE POWER ASSIST, AND SINCE THE ELECTRIC MOTORS WITHIN THE HYDRAULIC UNIT AND THE REAR BRAKE DRUMS ARE SEPARATELY DISABLED DURING S5.1.2 TESTING, THERE IS NO NEED TO SEPARATELY CONSIDER THESE ELECTRIC MOTORS WHEN CERTIFYING TO THE REQUIREMENTS OF S5.1.3.

Standard No. 105's requirements for inoperative brake power assist unit or brake power unit are set forth in S5.1.3. You stated that your planned brake system would not utilize conventional power assist, but brake power assist would be provided by the combination of the BCU and four electric motors. You stated that this design does not lend itself to an obvious way of distinguishing brake power assist from other service brake subsystem components, and suggested that the brake system be certified to the requirements of S5.1.3 by disabling the BCU (which would disable all four electric motors and completely eliminate functional brake power assist) and then satisfying the provisions of either S5.1.3.1, S5.1.3.2, or S5.1.3.4. You

also sought the agency's concurrence that there is no need to otherwise take the four electric motors into account when certifying to the requirements of S5.1.3.

S4 of Standard No. 105 defines the term "brake power assist unit" as a device installed in a hydraulic brake system that reduces the operator effort to actuate the system, and that if inoperative does not prevent the operator from braking the vehicle by a continued application of muscular force on the service brake control. Under the options of S5.1.3.1, S5.1.3.2, and S5.1.3.4, stopping distance requirements must be met with one brake power assist unit inoperative.

We believe that each electric motor comes within the definition of "brake power assist unit." In addition, given the integrated nature of the BCU and the four electric motors, we believe that the combination of the BCU/four electric motors also comes within the definition of "brake power assist unit." It is therefore our opinion that the requirements of S5.1.3 must be met both when the BCU is disabled (which would disable all four electric motors and completely eliminate functional brake power assist) and also when each of the four electric motors is disabled individually.

We note that, under our interpretation of S5.1.2 discussed above, not all of the four electric motors are separately disabled during S5.1.2 testing.

GM PROPOSED INTERPRETATION 7: THE GMEV BRAKE SYSTEM MAY BE CERTIFIED TO THE REQUIREMENTS OF S5.5 IN ACCORDANCE WITH THE TEST PROCEDURE OF S7.9.4 BY FUNCTIONALLY DISABLING THE BCU. SINCE SUCH A PROCEDURE WILL COMPLETELY DISABLE ABS AND THE VARIABLE PROPORTIONING FUNCTION, NO OTHER TESTING IS REQUIRED IN CONNECTION WITH S5.5.

Standard No.105's requirements for failed antilock and variable proportioning brake systems are set forth in S5.5. You stated that the BCU is the functional power source for the GMEV's ABS, and that the BCU also regulates the proportion of front to rear braking. You sought the agency's concurrence that disabling the BCU is the appropriate means of complying with S5.5, and is consistent with the procedure of S7.9.4.

S5.5 provides that a vehicle shall meet certain stopping distance requirements in the event of failure (structural or functional) in an antilock or variable proportioning brake system. S7.9.4 provides the following test procedure:

With vehicle at GVWR, disconnect functional power source, or otherwise render antilock system inoperative. Disconnect variable proportioning brake system. Make four stops, each from 60 mph. If more than one antilock or variable proportioning brake subsystem is provided, disconnect or render one subsystem inoperative and run as above. Restore system to normal at completion of this test. Repeat for each subsystem provided.

We concur that your planned brake system should be tested to the requirements of S5.5 in accordance with the test procedure of S7.9.4 by functionally disabling the BCU, and that no other testing is required. Under S7.9.4, the antilock system is to be rendered inoperative and the variable proportioning system is to be disconnected. Both of these procedures are accomplished by functionally disabling the BCU. Further, it is our opinion that the planned

brake system would not have antilock or variable proportioning subsystems, since antilock at all four wheels and variable proportioning are all controlled by the BCU.

GM PROPOSED INTERPRETATION 8: ASSUMING THE CONDITIONS ESTABLISHED IN PROPOSED S6.2, REGENERATIVE BRAKING IS PERMITTED TO FUNCTION NORMALLY WHEN CONDUCTING THE TEST PROCEDURES OF S7. IN PARTICULAR, THE PHRASE "SERVICE BRAKES SHALL BE CAPABLE OF STOPPING" (FOUND IN S5.1.4 AND S5.1.5, FOR EXAMPLE) IS NOT TO BE CONSTRUED AS PROHIBITING THE NORMAL OPERATION FOR REGENERATIVE BRAKING.

In addressing how the current requirements of Standard No. 105 would apply to your vehicle, we cannot assume the conditions you recommend establishing in a new S6.2. The agency would need to add those conditions to the standard in rulemaking. I will therefore address how regenerative braking would be treated under the current requirements.

As discussed in your letter, regenerative braking assists in decelerating the vehicle by converting the kinetic energy of the moving vehicle into stored electrical energy within the vehicle's battery pack. Regenerative braking on the planned GM electric vehicle will supplement, under certain conditions, the friction braking provided by the service brakes. You stated that regenerative braking will only be available when the vehicle is "in gear." Since the large majority of Standard No. 105 tests are conducted with the vehicle in "neutral," regenerative braking will have no influence on the outcome of those tests. You indicated that since some Standard No. 105 tests, notably fade and recovery and the water test, are conducted with the vehicle "in gear," regenerative braking could occur during these tests.

You stated that you believe that regenerative braking should generally be allowed to function normally during Standard No. 105 testing. You argued that the regenerative braking which may occur during "in gear" Standard No. 105 tests is little different from the engine braking which occurs in conventional ICE vehicles. We agree that regenerative braking should function normally during Standard No. 105 testing, just as engine braking occurs normally during Standard No. 105's "in gear" tests.

Another issue that you raised in connection with regenerative braking is the state of battery charge during testing, which can affect the amount of regenerative braking. You proposed (for your recommended new S6.2) that tests be initiated with a full charge of the vehicle's battery pack, so that the amount of regenerative braking that would occur during the tests would be minimized to the least amount that could occur in real world driving, i.e., the tests would be conducted under "worst case" conditions.

While Standard No. 105 specifies many test conditions, it does not specify state-of-battery charge. In an interpretation letter to Mazda dated October 2, 1990, we provided general guidance concerning how NHTSA interprets a standard where it does not specify a particular test condition. First, we stated that, in the absence of a particular test condition, we believe there is a presumption that the requirements need to be met regardless of such test

condition, since the standard does not include any language which specifically limits applicability of its requirements to such test condition. We also indicated, however, that before reaching such a conclusion, we also consider the language of the standard as a whole and its purposes.

It is our opinion that the braking requirements of Standard No. 105 must be met regardless of the state of battery charge. The purpose of Standard No. 105 is to ensure safe braking performance under normal and emergency conditions. Since an electric vehicle will be driven with the battery at various states of charge, safe braking performance can only be ensured if the standard's requirements can be met in all such conditions. This would generally be consistent with GM's suggestion that compliance testing be conducted under "worst case" conditions.

GM PROPOSED INTERPRETATION 9: IN ADDITION TO THE EXPLICIT CONDITIONS FOR ACTIVATION OF THE BRAKE TELLTALE SET FORTH IN S5.3 OF THE STANDARD, PERMIT ILLUMINATION OF THE SERVICE BRAKE TELLTALE WHEN AN IMPENDING OR LATENT BRAKE SYSTEM MALFUNCTION IS DETECTED DURING ELECTRICAL DIAGNOSIS.

As noted by your letter, S5.3.1 of Standard No. 105 requires a brake telltale to illuminate when there is a gross loss of hydraulic pressure (or, alternatively, a drop in fluid level), a total functional electrical failure in the antilock or variable proportioning brake system, and when the parking brake is applied. You stated that a brake telltale on the planned GMEV would illuminate under these prescribed conditions. Yon indicated, however, that a diagnostic capability will also exist to detect other faults in the brake system, and requested the agency's concurrence that S5.3.1 permits illumination of the brake telltale when other faults are detected which increase the likelihood of a substantial degradation in brake system performance.

While Standard No. 105 requires that a brake telltale be provided which activates under certain specified conditions, it does not expressly state whether the required telltale may also be activated under other conditions. It is our opinion that the telLtale may also activate under other conditions so long as such activation does not obscure or confuse the meaning of the required telltale or otherwise defeat its purpose. I note that this test is similar to one the agency has long used in addressing the issue of whether additional information may be provide along with information that is required to be labeled on certain products in the context of our safety standards. See, for example, NHTSA's December 20, 1991 interpretation letter to GM concerning Standard No. 209.

The purpose of the brake telltale is to warn the driver of one of two conditions: (1) the parking brake is applied (and hence should be released before driving), or (2) the brake system has a significant fault which should be corrected. Since the additional conditions for activation which GM contemplates would represent significant brake system faults which should be corrected, it is our opinion that activation of the brake telltale under such conditions would not in any way defeat the purpose of the brake telltale.

I hope you find this information helpful. If you have further questions, please contact Edward Glancy of my staff at this address or by telephone at (202) 366-2992.

ID: aiam0003

"Dear Mr. Selander: This responds to your February 17, 1992 request fo interpretations of Federal Motor Vehicle Safety Standards No. 101, Controls and Displays and No. 105, Hydraulic Brake Systems, as those standards would apply to an electric vehicle (GMEV) that General Motors (GM) is preparing to sell in the future. You requested the agency's concurrence with, or guidance regarding, nine proposed interpretations. Your questions are addressed below. Before discussing the substantive issues that you raised, I note that you requested confidential treatment for portions of certain materials that you provided relating to the brake system planned for the electric vehicle. These materials were previously submitted to NHTSA, and the agency granted confidentiality for portions of the materials in letters dated July 18, 1991 and August 12, 1991. In a letter accompanying your request for interpretation, GM released from its request for confidential treatment portions of the materials for which confidentiality had previously been granted. NHTSA's earlier grants of confidentiality remain in effect for the remaining portions for which GM continues to seek confidential treatment. Accordingly, this letter does not cite any of the confidential information. I also note that, in one of the attachments to your letter, you suggested several amendments to Standard No. 105 that you believe would facilitate the introduction of electric vehicles. As you know, NHTSA recently issued an advance notice of proposed rulemaking (ANPRM) to solicit comments to help the agency determine what existing standards may need modification to meet the needs associated with the introduction of electric vehicles and what new standards may have to be written specifically for electric vehicles. See 56 FR 67038, December 27, 1991. We will consider your recommendations concerning Standard No. 105 as we evaluate the comments on the ANPRM. The scope of this letter is limited to addressing how the current requirements of Standards No. 101 and No. 105 would apply to your planned vehicle. By way of background information, NHTSA does not provide approvals of motor vehicles or motor vehicle equipment. Under the National Traffic and Motor Vehicle Safety Act, it is the responsibility of the manufacturer to ensure that its vehicles and equipment comply with applicable requirements. The following represents our opinion based on the facts provided in your letter. Standard No. 101, Controls and Displays GM Proposed Interpretation 1: Permit electrically powered vehicles to use symbols that are appropriate for indicating electric power reserve. You asked two questions regarding how Standard No. 101 would apply to the GM electric vehicle. The first question concerned the identification for a gauge that would monitor battery charge as a percent of full charge. This gauge would serve as the functional equivalent of a fuel gauge in traditional internal combustion engine (ICE) vehicles. You stated, however that it would be inappropriate and potentially misleading to use Standard No. 101's fuel symbol (a picture of a gasoline pump) for a gauge indicating electric power reserve. You stated that you planned to identify the gauge with the ISO battery symbol (a picture of a battery), which you indicated is substantially similar to that found in Standard No. 101 for electrical charge. You requested NHTSA's concurrence that electric vehicles are permitted to use symbols that are appropriate for identifying electric power reserve and not the Standard No. 101 fuel symbol. Standard No. 101 requires that new vehicles with any display listed in the standard must meet specified requirements for the location, identification and illumination of such display. See S5(a). Thus, the primary issue raised by your question is whether a gauge indicating electric power reserve is among the displays listed in the standard, and if so, what identification requirements apply. As you noted in your letter, one of the displays listed in Standard No. 101 is a fuel gauge. See S5.1 and Table 2. The dictionary defines 'fuel' as combustible matter used to maintain fire, as coal, wood, oil, etc. See Random House Dictionary of the English Language (unabridged edition). Electrical power provided by a battery does not come within the meaning of 'fuel.' Therefore, a gauge indicating electric power reserve for an electric vehicle is not a fuel gauge. Another display listed in Standard No. 101 is an electrical charge gauge. This term refers to gauges that indicate whether, and the extent to which, a vehicle's battery is charging. Therefore, a gauge indicating electric power reserve for an electric vehicle is not an electric charge gauge within the meaning of Standard No. 101. Since a gauge indicating electric power reserve is not otherwise covered by Standard No. 101 or any other standard, its identification is at the option of the manufacturer. GM Proposed Interpretation 2: Allow the 'Service Soon' telltale to indicate loss of powertrain oil pressure for the GMEV. Your second question concerned whether low oil pressure may be indicated by activation of a 'Service Soon' telltale instead of one identified by Standard No. 101's oil pressure symbol (a picture of an oil can) or the word 'oil.' You stated that a 'Service Soon' telltale would be more appropriate for an electric vehicle, since it (unlike ICE vehicles) can continue to be driven without oil pressure. One of the displays listed in Standard No. 101 is an oil pressure telltale. While the seriousness of low oil pressure may be different for electric vehicles than ICE vehicles, the condition for activation of an oil pressure telltale (low oil pressure) would be the same. It is our opinion that Standard No. 101's identification requirements would apply to an oil pressure telltale for an electric vehicle. If a manufacturer is concerned that the oil pressure symbol or the word 'oil' might be misleading to drivers familiar with ICE vehicles, the manufacturer is free to provide additional words or symbols for the purpose of clarity. See S5.2.3. It is not clear, however, that the telltale you plan would be considered a low oil pressure telltale within the meaning of Standard No. 101. You state that, as currently planned, the electric vehicle will be equipped with a 'Service Soon' telltale which will light in the event of a malfunction that could eventually cause damage to the vehicle powertrain, but does not require immediate attention. It thus appears that the telltale might monitor several possible vehicle conditions, one of which is low oil pressure. Standard No. 101 does not require that any of the displays listed in the standard be provided or that two or more displays, if provided, be provided separately. NHTSA has previously concluded that a multipurpose telltale which monitors two functions, oil pressure and coolant temperature, may be identified by the word 'Engine.' See December 29, 1978 letter to Ford Motor Company. The basis for this interpretation was that while Standard No. 101 specifies requirements for oil pressure and coolant temperature telltales, it does not specify any requirements for a single telltale which covers both conditions. For the same reason, if GM provided a single telltale monitoring several vehicle conditions, one of which was low oil pressure, the standard's requirements for an oil pressure telltale would not apply and the identification for that telltale would be at the discretion of the manufacturer. Standard No. 105, Hydraulic Brake Systems You asked seven questions regarding how Standard No. 105 would apply to the GM electric vehicle. You provided the following general description of the brake system planned for the vehicle: The brake system consists of front hydraulic disc (service) brakes, rear electric drum (service and parking) brakes, four-wheel ABS, and regenerative braking. Brake pedal forces and travel are comparable to conventional power assisted hydraulic brake systems, and are independent of the state-of-charge of the vehicle's battery pack. The design features a manual hydraulic 'push through' to apply the front brakes in the event of any electrical failure. Standard No. 105 applies to passenger cars and various other vehicle types with 'hydraulic service brake systems.' See S3. Since the service brakes of the GM electric vehicle would be partly hydraulic brakes and partly electric brakes, a preliminary issue is whether the standard would apply to the vehicle. As discussed below, it is our opinion that the standard would apply to the vehicle. The term 'hydraulic brake system' is defined in S4 as 'a system that uses hydraulic fluid as a medium for transmitting force from a service brake control to the service brake, and that may incorporate a brake power assist unit, or a brake power unit.' The term 'service brake' is defined at Part 571.3 as 'the primary mechanism designed to stop a motor vehicle.' The planned braking system would use hydraulic fluid as a medium for transmitting force from the service brake control to the front brake portion of the service brake. It is our interpretation that this is sufficient, under the definition of 'hydraulic brake system,' for the braking system to be considered a 'hydraulic brake system,' even though hydraulic fluid is not used for the rear brake portion of the service brake. Therefore, Standard No. 105 would apply to the vehicle. GM Proposed Interpretation 3: The GMEV parking brake is mechanically retained in accordance with the requirements of S5.2. Your first question on Standard No. 105 concerned S5.2's requirement that vehicles be manufactured 'with a parking brake system of a friction type with a solely mechanical means to retain engagement.' You stated that the parking brake on the GMEV would be applied and released by electrical means, but would be retained by a mechanical latching device. You requested NHTSA's concurrence that the planned parking brake would satisfy the requirement for mechanically retained engagement. We agree that S5.2 permits the parking brake to be applied and released by electrical or other non-mechanical means, so long as engagement is held by solely mechanical means. Your next several questions concern Standard No. 105's brake failure requirements. As noted by your letter, these requirements are set forth in S5.1.2 (partial failure), S5.1.3 (inoperative brake power assist unit or brake power unit), and S5.5 (failure in antilock or variable proportioning brake system), and the test procedures for these requirements are set forth in S7.9 and S7.10. GM Proposed Interpretation 4: The subject brake system is a 'split service brake system' consisting of four subsystems--one at each wheel. Standard No. 105 specifies different partial failure requirements depending on whether a vehicle is manufactured with a split service brake system. The term 'split service brake system' is defined in S4 as 'a brake system consisting of two or more subsystems actuated by a single control designed so that a leakage- type failure of a pressure component in a single subsystem (except structural failure of a housing that is common to two or more subsystems) shall not impair the operation of any other subsystem.' We agree that your planned vehicle can be viewed as having four subsystems, one at each wheel. In only two of the subsystems, however, can leakage-type failures occur (the two hydraulic subsystems). Thus, in determining whether the vehicle has a split service brake system within the meaning of Standard No. 105, the key is whether a leakage-type failure of a pressure component in either of those two subsystems (except structural failure of a housing that is common to two or more subsystems) impairs the operation of any other subsystem (i.e., the other hydraulic subsystem or either of the two other subsystems). After reviewing the information provided with your letter, we have no reason to doubt that your planned system qualifies as a split service brake system. GM Proposed Interpretation 5: The four service brake subsystems may be certified to the requirements of S5.1.2 in accordance with the test procedure of S7.9.1 through S7.9.3 by disabling each subsystem in a way that does not affect the other three subsystems. Standard No. 105's requirements for partial failure are set forth in S5.1.2. For vehicles with a split service brake system, 5.1.2.1 provides that, in the event of a rupture or leakage type of failure in a single subsystem, other than a structural failure of a housing that is common to two or more subsystems, the remaining portion(s) of the service brake system shall continue to operate and shall be capable of stopping a vehicle from 60 mph within specified stopping distances. You suggested that certification of the requirements of S5.1.2.1, consistent with the procedure of S7.9.1 through S7.9.3, should be established by disabling each of the four subsystems in turn. You also stated that, for purposes of compliance testing, the subsystems would be disabled in such a way that the functioning of only one subsystem would be affected. It is our opinion that, in testing under S5.1.2.1, only the two hydraulic subsystems of your planned brake system would be disabled, as S5.1.2.1 only addresses rupture/leakage types of failures. It does not address any type of failure of a subsystem for which a rupture or leakage type failure cannot occur. We would not consider a break in an electrical system to be a 'rupture' within the meaning of Standard No. 105. We are uncertain as to the meaning of your statement that, for purposes of compliance testing, the subsystems would be disabled in such a way that the functioning of only one subsystem would be affected. This could be read as meaning that the agency must induce a rupture or leakage type failure in a place that doesn't affect other subsystems. However, under S7.9.1, any one rupture or leakage type of failure is introduced, other than a structural failure of a housing that is common to two or more subsystems. If any such leakage type failure impaired another subsystem, the brake system would not, of course, be considered a split service brake system within the meaning of Standard No. 105. GM Proposed Interpretation 6: The GMEV brake system may be certified to the requirements of S5.1.3 in accordance with the test procedure of S7.10 by functionally disabling the BCU. Such a procedure will completely disable the brake power assist, and since the electric motors within the hydraulic unit and the rear brake drums are separately disabled during S5.1.2 testing, there is no need to separately consider these electric motors when certifying to the requirements of S5.1.3. Standard No. 105's requirements for inoperative brake power assist unit or brake power unit are set forth in S5.1.3. You stated that your planned brake system would not utilize conventional power assist, but brake power assist would be provided by the combination of the BCU and four electric motors. You stated that this design does not lend itself to an obvious way of distinguishing brake power assist from other service brake subsystem components, and suggested that the brake system be certified to the requirements of S5.1.3 by disabling the BCU (which would disable all four electric motors and completely eliminate functional brake power assist) and then satisfying the provisions of either S5.1.3.1, S5.1.3.2, or S5.1.3.4. You also sought the agency's concurrence that there is no need to otherwise take the four electric motors into account when certifying to the requirements of S5.1.3. S4 of Standard No. 105 defines the term 'brake power assist unit' as a device installed in a hydraulic brake system that reduces the operator effort to actuate the system, and that if inoperative does not prevent the operator from braking the vehicle by a continued application of muscular force on the service brake control. Under the options of S5.1.3.1, S5.1.3.2, and S5.1.3.4, stopping distance requirements must be met with one brake power assist unit inoperative. We believe that each electric motor comes within the definition of 'brake power assist unit.' In addition, given the integrated nature of the BCU and the four electric motors, we believe that the combination of the BCU/four electric motors also comes within the definition of 'brake power assist unit.' It is therefore our opinion that the requirements of S5.1.3 must be met both when the BCU is disabled (which would disable all four electric motors and completely eliminate functional brake power assist) and also when each of the four electric motors is disabled individually. We note that, under our interpretation of S5.1.2 discussed above, not all of the four electric motors are separately disabled during S5.1.2 testing. GM Proposed Interpretation 7: The GMEV brake system may be certified to the requirements of S5.5 in accordance with the test procedure of S7.9.4 by functionally disabling the BCU. Since such a procedure will completely disable ABS and the variable proportioning function, no other testing is required in connection with S5.5. Standard No.105's requirements for failed antilock and variable proportioning brake systems are set forth in S5.5. You stated that the BCU is the functional power source for the GMEV's ABS, and that the BCU also regulates the proportion of front to rear braking. You sought the agency's concurrence that disabling the BCU is the appropriate means of complying with S5.5, and is consistent with the procedure of S7.9.4. S5.5 provides that a vehicle shall meet certain stopping distance requirements in the event of failure (structural or functional) in an antilock or variable proportioning brake system. S7.9.4 provides the following test procedure: With vehicle at GVWR, disconnect functional power source, or otherwise render antilock system inoperative. Disconnect variable proportioning brake system. Make four stops, each from 60 mph. If more than one antilock or variable proportioning brake subsystem is provided, disconnect or render one subsystem inoperative and run as above. Restore system to normal at completion of this test. Repeat for each subsystem provided. We concur that your planned brake system should be tested to the requirements of S5.5 in accordance with the test procedure of S7.9.4 by functionally disabling the BCU, and that no other testing is required. Under S7.9.4, the antilock system is to be rendered inoperative and the variable proportioning system is to be disconnected. Both of these procedures are accomplished by functionally disabling the BCU. Further, it is our opinion that the planned brake system would not have antilock or variable proportioning subsystems, since antilock at all four wheels and variable proportioning are all controlled by the BCU. GM Proposed Interpretation 8: Assuming the conditions established in proposed S6.2, regenerative braking is permitted to function normally when conducting the test procedures of S7. In particular, the phrase 'service brakes shall be capable of stopping' (found in S5.1.4 and S5.1.5, for example) is not to be construed as prohibiting the normal operation for regenerative braking. In addressing how the current requirements of Standard No. 105 would apply to your vehicle, we cannot assume the conditions you recommend establishing in a new S6.2. The agency would need to add those conditions to the standard in rulemaking. I will therefore address how regenerative braking would be treated under the current requirements. As discussed in your letter, regenerative braking assists in decelerating the vehicle by converting the kinetic energy of the moving vehicle into stored electrical energy within the vehicle's battery pack. Regenerative braking on the planned GM electric vehicle will supplement, under certain conditions, the friction braking provided by the service brakes. You stated that regenerative braking will only be available when the vehicle is 'in gear.' Since the large majority of Standard No. 105 tests are conducted with the vehicle in 'neutral,' regenerative braking will have no influence on the outcome of those tests. You indicated that since some Standard No. 105 tests, notably fade and recovery and the water test, are conducted with the the vehicle 'in gear,' regenerative braking could occur during these tests. You stated that you believe that regenerative braking should generally be allowed to function normally during Standard No. 105 testing. You argued that the regenerative braking which may occur during 'in gear' Standard No. 105 tests is little different from the engine braking which occurs in conventional ICE vehicles. We agree that regenerative braking should function normally during Standard No. 105 testing, just as engine braking occurs normally during Standard No. 105's 'in gear' tests. Another issue that you raised in connection with regenerative braking is the state of battery charge during testing, which can affect the amount of regenerative braking. You proposed (for your recommended new S6.2) that tests be initiated with a full charge of the vehicle's battery pack, so that the amount of regenerative braking that would occur during the tests would be minimized to the least amount that could occur in real world driving, i.e., the tests would be conducted under 'worst case' conditions. While Standard No. 105 specifies many test conditions, it does not specify state-of-battery charge. In an interpretation letter to Mazda dated October 2, 1990, we provided general guidance concerning how NHTSA interprets a standard where it does not specify a particular test condition. First, we stated that, in the absence of a particular test condition, we believe there is a presumption that the requirements need to be met regardless of such test condition, since the standard does not include any language which specifically limits applicability of its requirements to such test condition. We also indicated, however, that before reaching such a conclusion, we also consider the language of the standard as a whole and its purposes. It is our opinion that the braking requirements of Standard No. 105 must be met regardless of the state of battery charge. The purpose of Standard No. 105 is to ensure safe braking performance under normal and emergency conditions. Since an electric vehicle will be driven with the battery at various states of charge, safe braking performance can only be ensured if the standard's requirements can be met in all such conditions. This would generally be consistent with GM's suggestion that compliance testing be conducted under 'worst case' conditions. GM Proposed Interpretation 9: In addition to the explicit conditions for activation of the brake telltale set forth in S5.3 of the standard, permit illumination of the service brake telltale when an impending or latent brake system malfunction is detected during electrical diagnosis. As noted by your letter, S5.3.1 of Standard No. 105 requires a brake telltale to illuminate when there is a gross loss of hydraulic pressure (or, alternatively, a drop in fluid level), a total functional electrical failure in the antilock or variable proportioning brake system, and when the parking brake is applied. You stated that a brake telltale on the planned GMEV would illuminate under these prescribed conditions. You indicated, however, that a diagnostic capability will also exist to detect other faults in the brake system, and requested the agency's concurrence that S5.3.1 permits illumination of the brake telltale when other faults are detected which increase the likelihood of a substantial degradation in brake system performance. While Standard No. 105 requires that a brake telltale be provided which activates under certain specified conditions, it does not expressly state whether the required telltale may also be activated under other conditions. It is our opinion that the telltale may also activate under other conditions so long as such activation does not obscure or confuse the meaning of the required telltale or otherwise defeat its purpose. I note that this test is similar to one the agency has long used in addressing the issue of whether additional information may be provided along with information that is required to be labeled on certain products in the context of our safety standards. See, for example, NHTSA's December 20, 1991 interpretation letter to GM concerning Standard No. 209. The purpose of the brake telltale is to warn the driver of one of two conditions: (1) the parking brake is applied (and hence should be released before driving), or (2) the brake system has a significant fault which should be corrected. Since the additional conditions for activation which GM contemplates would represent significant brake system faults which should be corrected, it is our opinion that activation of the brake telltale under such conditions would not in any way defeat the purpose of the brake telltale. I hope you find this information helpful. If you have further questions, please contact Edward Glancy of my staff at this address or by telephone at (202) 366-2992. Sincerely, Paul Jackson Rice Chief Counsel";