ID: NCC-241023-001TSEI-TIMA Letter of Interpretation 571.108 Flashing Amber Lights 12-13-2024.signed.

December 13, 2024

Mr. Chuck Polley

Transportation Safety Equipment Institute

c/o Grote Industries LLC

2600 Lanier Drive

Madison, IN 47250

Mr. John Freiler

Truck Trailer Manufacturers Association

7001 Heritage Village Plaza

Suite 220

Gainesville, VA 20155-3094

Dear Messrs. Polley and Freiler:

This responds to your letter requesting clarification of Federal Motor Vehicle Safety Standard (FMVSS) No. 108, Lamps, reflective devices, and associated equipment, regarding flashing “emergency warning lights.” I apologize for the delay in responding. As used in your letter, the term “emergency warning lights” generically refers to a category of vehicle lighting equipment that consists of one or more amber-colored flashing or strobing lamps that is typically installed on certain types of slow-moving vehicles and utility vehicles (such as tow trucks, repair vehicles, or vehicles transporting oversized loads) to call the attention of other drivers to the presence of these vehicles. 

You ask that the National Highway Traffic Safety Administration (NHTSA) provide clarification of its longstanding interpretations of FMVSS No. 108 and permit original equipment installation of “emergency warning lights.” Alternatively, you ask that NHTSA issue guidance regarding the circumstances under which such lighting may be installed by vehicle manufacturers or repair businesses without violating the “make inoperative” provision of the National Traffic and Motor Vehicle Safety Act (Safety Act) (49 U.S.C. §§ 30101 et seq.). 

In responding to this request, NHTSA notes that the contents of this letter do not have the force and effect of law and are not meant to bind the public in any way. This letter is only intended to provide clarity regarding existing requirements under the law at the time of signature. 

After carefully considering your letter, we reaffirm our previous interpretations that, under current law, “emergency warning lights” may not be installed as original equipment and that persons subject to the make inoperative provision of the Safety Act may not legally install the lamps as original or aftermarket equipment. We explain our reasoning below, based on our understanding of the information you present. 

Background 

FMVSS No. 108 specifies requirements for original and replacement lamps, reflective devices, and associated equipment. For auxiliary lamps, the primary restriction imposed by FMVSS No. 108 is in S6.2.1, which states that “[n]o additional lamp, reflective device, or other motor vehicle equipment is permitted to be installed that impairs the effectiveness of lighting equipment required by this standard.” Additionally, both original equipment and aftermarket lighting can run afoul of the “make inoperative” provision, and NHTSA considers the installation of an aftermarket lamp to violate the “make inoperative” provision if the installation of the same lamp as original equipment would violate FMVSS No. 108.1 Whether there is an impairment is determined in the first instance by the manufacturer of the vehicle (or the entity installing the aftermarket lighting) when it is certified as compliant with FMVSS No. 108. NHTSA may contest such a determination if it is clearly erroneous.2 These prohibitions bar installation by a manufacturer, distributor, dealer, rental company, or motor vehicle repair business of lamps that would impair the effectiveness of required lighting, but do not apply to the owner of a vehicle. 

Typically, the impairment determination is made on a case-by-case basis and considers several characteristics of the auxiliary lamp, such as the brightness, color, location, and activation pattern of the lamp, to analyze whether it impairs the effectiveness of required lighting. This list of characteristics is not exhaustive and other considerations may be relevant to the analysis. NHTSA has long maintained that highway traffic safety is enhanced by the drivers’ familiarity with established lighting schemes, which enables them to instantly recognize the meaning the lamps convey and respond accordingly. NHTSA has long interpreted FMVSS No. 108 to require that all auxiliary lamps be “steady burning,” with the sole exception of auxiliary lamps that supplement required lamps that flash, such as turn signals.3 

Discussion 

NHTSA’s longstanding interpretation of FMVSS No. 108 is that the standard does not permit the “emergency warning lights” to be installed as original equipment because they are auxiliary lighting that is not steady burning and would impair the effectiveness of required lamps by causing confusion among other drivers about the meaning of required lighting or distracting drivers from required lighting.4 Further, because “emergency warning lights” would impair the effectiveness of required lamps, NHTSA has also determined that entities listed in § 30122 of the Safety Act that install “emergency warning lights” on new or used vehicles would violate the “make inoperative” provision of the Act. 

Notwithstanding those interpretations, you provide various reasons why you believe that “current regulations permit manufacturers to install such supplemental lighting as original equipment.” We respond to your reasons below. 

1 E.g., Letter to Timothy C. Murphy (Nov. 1, 2004), available at https://www.nhtsa.gov/interpretations/gf006332.
2 Letter from John Womack to Larry Grabsky (Nov. 16, 1993), available at https://www.nhtsa.gov/interpretations/9251.
3 See, e.g., Letter to Richard Seoane (June 27, 2024), available at https://www.nhtsa.gov/interpretations/ncc-231121- 001-autoliv-veoneer-spotlight-interpretation-1; and Letter to Paul Schaye (Sept. 9, 2019), available at https://www.nhtsa.gov/interpretations/571108-ama-schaye-front-color-changing-light.
4 Letter to J. Adam Krugh IV (May 22, 2003), available at https://www.nhtsa.gov/interpretations/002769drn (explaining that a flashing or strobing lamp on top of a school bus would impair the effectiveness of required signal lamps by diverting other drivers’ attention and causing confusion). 

Administrative Rewrite of FMVSS No. 108. First, you state that in an administrative rewrite of FMVSS No. 108, NHTSA removed explicit language in the standard that had contained a provision requiring that all lamps be steady burning unless otherwise indicated. You argue that the removal of this provision indicated an intention to loosen the restriction that auxiliary lamps must be steady burning when activated. 

NHTSA had no such intention. The removal of the referenced “steady burning” language in the FMVSS No. 108 administrative rewrite did not change the underlying substantive requirements that had applied to auxiliary lighting. Before it was modified in 2007, FMVSS No. 108 included an explicit requirement that, with the exception of certain types of required lamps (e.g., turn signal lamps), all lamps on a vehicle, including auxiliary lamps, must be steady burning. In 2007, NHTSA implemented an administrative reorganization of FMVSS No. 108 which, among other things, clarified the blanket “steady burning” requirement (and its exceptions) by converting it into specified individual activation requirements for each type of required lamp.5 Although the reorganized rule no longer includes a blanket “steady burning” requirement, NHTSA stated in the preamble to the reorganized rule that its “rewrite of FMVSS No. 108 is considered administrative in nature because the standard’s existing requirements and obligations are not being increased, decreased, or substantively modified.”6 Further, NHTSA continues to believe that flashing auxiliary lamps would impair the effectiveness of required lamps by distracting or confusing other road users and we have continued to restrict flashing or strobing auxiliary lamps since the rewrite except under a few limited circumstances not relevant here.7 Therefore, because the “emergency warning lights” are not steady burning, they would not comply with FMVSS No. 108 and would impair required lighting. 

Motorists are Used to “Emergency Warning Lights.” Second, you state that one of NHTSA’s reasons for disallowing flashing auxiliary lamps—their tendency to divert attention and cause confusion—is no longer valid for “emergency warning lights” because “the use of flashing-amber lighting has become widespread.” You provide no data or information to support this assertion, except to refer to past agency letters which discussed the make inoperative provision as applied to owners installing flashing or strobe lamps on their own vehicles, including a state installing the lamps on state-regulated emergency vehicles. 

We disagree with your assertion that the letters are indicative of the pervasiveness of “emergency warning lights.” The interpretation letters to which you refer do not endorse the installation of flashing or strobe lamps by individuals or declare that the lights do not impair the effectiveness of required lamps. Rather, those letters simply recognize the limits of NHTSA’s authority under the Safety Act to regulate aftermarket lighting equipment. The agency made, and continues to make, no determination as to whether the flashing amber lights are “widespread.”

5 72 FR 68234 (Dec. 4, 2007).
6 Id.
7 These exceptions include auxiliary lamps that supplement required flashing lamps like turn signals. See Letter to Jerry Koh (Feb. 6, 1986), available at https://www.nhtsa.gov/interpretations/86-250; see also Letter to Lt. Col. Steve Flaherty (May 2, 2003), available at https://www.nhtsa.gov/interpretations/flaherty (deference to states applies to “the installation and use of emergency lighting devices on [undercover state police] vehicles”). 

NHTSA has long believed that flashing amber lighting can unduly divert driver attention and cause confusion among drivers, even among those who have seen them before. As we have stated, “traffic safety is enhanced by the familiarity of drivers with established lighting schemes, which facilitates their ability to instantly and unhesitatingly recognize the meaning lamps convey and respond to them.”8 Flashing amber lighting, except for turn signal lamps, is not “an established lighting scheme” within the context of FMVSS No. 108. The meaning of flashing lights can vary depending on the nature of the vehicle on which they are installed, the context in which they are used, and state or local laws. Motorists might not know if the flashing amber lamps are meant to signal the presence of the vehicle for general driver awareness or the need for drivers to yield the right-of-way or perform some other driving task. The use of flashing amber lights is not sufficiently established and standardized to avoid unduly diverting driver attention or causing confusion. Thus, we continue to believe these lights impair required lighting equipment.9 

Other Federal Regulations and State Laws Recognizing “Emergency Warning Lights.”
Finally, you argue that permitting flashing amber auxiliary lamps as original equipment would “harmonize” NHTSA’s requirements with Federal Motor Carrier Safety Administration (FMCSA) regulations and state laws. You state that an FMCSA regulation (49 C.F.R. § 393.25(e)) permits the use of flashing lights on several vehicle types and that a change in NHTSA’s approach would better ensure such lighting is properly wired and installed. We are also aware of exemptions granted by FMCSA permitting certain entities to use pulsating brake-activated amber lights as well as the operation of commercial motor vehicles equipped with the Intellistop device.10 

Our longstanding interpretation of FMVSS No. 108 regarding flashing auxiliary lights is not impacted by these FMCSA regulations, exemptions, or state laws. The FMCSA regulation does not require the flashing lamps to be installed as original equipment or by an entity subject to the make inoperative provision. Additionally, although you allude to safety concerns about owners improperly wiring or installing emergency warning lights on their vehicles to comply with state laws, we are not aware of any state laws requiring installation of these lights specifically as original equipment or by an entity subject to the make inoperative requirement. Nor is allowing installation by such entities necessary to address improper owner installations of these lights. 

If you have further questions, please contact Eli Wachtel of my staff at (202) 366-2992.

Sincerely,
ADAM RAVIV
Adam Raviv Chief Counsel
 

Dated:12/13/24
Ref: Standard No. 108

8 Letter to J. Adam Krugh IV (May 22, 2003), available at https://www.nhtsa.gov/interpretations/002769drn.
9 Nothing in this letter is intended to conflict with our interpretation, stated in our May 2, 2003, Letter to Lt. Col. Steve Flaherty, that deference to states applies to “the installation and use of emergency lighting devices on [the state’s] vehicles.” Letter available at https://www.nhtsa.gov/interpretations/flaherty.
10 List of FMCSA exemptions in effect available at https://www.fmcsa.dot.gov/exemptions.

ID: NCC-241028-001 Interp Response - Volvo Trucks - FMVSS 121 Air Brake Reservoirs 01.16.2025

January 16, 2025

Mac Bradley Principal Engineer 

Volvo Group Trucks Technology 

Volvo Group North America LLC 

7900 National Service Road 

Greensboro, NC 27409

Re:    Interpretation of Air Brake System reservoir requirements under Standard No. 121 

Dear Mr. Bradley: 

This responds to your letter dated May 23, 2018, on behalf of Volvo Group North America LLC regarding the air brake system reservoir requirements in Federal Motor Vehicle Safety Standard (FMVSS) No. 121, S5.1.2. You describe a technology where an air dryer feeds the service reservoir directly, without the use of a separate supply reservoir or a condensate drain valve. You asked whether technology that you find to be “demonstratively more effective than a supply reservoir or automatic drain valve” may be used to comply with S5.1.2’s requirements. This letter responds to that request. 

In responding, the National Highway Traffic Safety Administration (NHTSA) notes that the contents of this letter do not have the force and effect of law and are not meant to bind the public in any way. This letter is only intended to provide clarity regarding existing requirements under the law at the time of signature. 

Section 5.1.2 requires that each truck and bus shall have:  

One or more service reservoir systems, from which air is delivered to the brake chambers, and either an automatic condensate drain valve for each service reservoir or a supply reservoir between the service reservoir system and the source of air pressure. 

S5.1.2 provides explicit reservoir requirements. Without either an automatic condensate drain valve or a supply reservoir, a vehicle would not comply with S5.1.2. The air dryer technology you suggest includes neither a condensate drain valve nor a supply reservoir. Although you suggest that this new technology is at least equally effective at removing water from compressed air, the standard is specific in its equipment requirements. We cannot by interpretation remove the requirements set forth in express terms in the regulatory text.1 

1 See, e.g., Letter to R.W. Hildebrandt, Bendix Corp. (May 30, 1980), available at www.nhtsa.gov/interpretations/nht80-241 (finding non-compliance where the air brake system may comply with the alleged intent of FMVSS No. 121 but does not comply with the standard’s technical requirements). 

The Notice of Proposed Rulemaking you cited from 1996 did propose revising FMVSS No. 121 to require a means of automatically removing moisture and contaminants from the air system and to delete the requirement for a supply reservoir. See 61 F.R. 56652 (Nov. 4, 1996). However, after consideration, NHTSA terminated that rulemaking, opting for further study of the requirements and test procedures for air drying and cleansing equipment used in air brake systems. See 63 F.R. 14674 (May 26, 1998). 

NHTSA cannot amend its regulations by interpretation. The appropriate vehicle to present your arguments would be a petition for rulemaking to amend FMVSS No. 121. In such a petition, you would be free to rely on the data you shared regarding the efficacy of air dryers at removing water from compressed air in support of a such petition for rulemaking. 

I hope this information is helpful. If you have any further questions, please feel free to contact Evita St. Andre of my staff at this address or (617) 494-2767. 

Sincerely,
ADAM RAVIV

Adam Raviv Chief Counsel
 

Dated: 1/16/25
Ref: Standard No. 121

ID: 571.108 School Bus Focused Illuminated Projection Lanyon NCC-230125-001

March 21, 2023

Mr. Bobby Lanyon
Access Innovations Global LP dba AIG Safety
PO Box 511
Orefield, PA 18069 

Dear Mr. Lanyon,  

This letter responds to your request that the National Highway Traffic Safety Administration (NHTSA) allow, but not mandate, your company’s product, the “Focused Illuminated Projection” system, for application on school buses under Federal Motor Vehicle Safety Standard (FMVSS) No. 131, School bus pedestrian safety devices. Your request was referred to my office to determine whether the feature you describe is allowed under existing FMVSSs. While you asked for an amendment to FMVSS No. 131, we believe it is appropriate to consider whether your product would be permitted as an auxiliary lighting device under FMVSS No. 108, Lamps, reflective devices, and associated equipment. Based on the information you have provided, our answer is that your device is permissible under FMVSS No. 108 for the reasons explained below. 

By way of background, NHTSA does not provide approvals of motor vehicles or motor vehicle equipment. Instead, manufacturers are required to self-certify that their products conform to all applicable FMVSSs that are in effect on the date of manufacture before the products can be offered for sale. Manufacturers must also ensure their products are free of safety-related defects. This letter represents NHTSA’s opinion concerning whether your product, as you describe it, would be permitted under FMVSS No. 108. It is not an approval of your product, nor is it an endorsement of the safety claims made in your interpretation request.  

Under FMVSS No. 108 S6.2.1, non-required additional lamps are prohibited on new
vehicles if they impair the effectiveness of lighting devices required by FMVSS No. 108. The question as to whether an auxiliary lamp impairs required lighting equipment is usually decided on a case-by-case basis.1 Based on the information you have provided, we have concluded that the “Focused Illuminated Projection” system will not impair the effectiveness of a school bus’s required lighting. 

1 Letter to Michael Haas (May 6, 2019), available at https://isearch.nhtsa.gov/files/571.108%20--%20HDC%20Supplemental%20Turning%20Lamps%20--%20HAAS%20--%2015-4155.htm. 

Page 2
Mr. Bobby Lanyon 

Description of the “Focused Illuminated Projection” system 

Your letter describes the system as a “low technology, high reliability solution designed and implemented to re-enforce the explicit and implied scope (S1) and Purpose (S2) of Section 571.131 by statically illuminating the 10ft stopping threshold” onto the roadway in front of and behind a school bus during a school bus stop. AIG also describes it as creating an “illuminated crosswalk” for students. 

The system consists of red LED lights mounted onto the front and rear of the bus adjacent to or below the signal warning lamps above the front windshield or rear window. It projects a red line onto the road 10 feet in front of and behind the bus. It is controlled by the “same electrical relay that illuminates” the lamps on the stop signal arm. We assume, for the purposes of this interpretation, that this device only activates when the vehicle is stopped and is in a loading/unloading state, when the stop arm is also activated or the door is open. 

Discussion 

FMVSS No. 108 requires that school buses be equipped with a system of two red signal lamps, and optionally two amber signal lamps, installed at both the top front and top rear. These lamps must flash alternately at a rate of 60-120 cycles per minute. We have previously stated that auxiliary lamps can impair the effectiveness of required lighting in four ways: brightness, activation pattern, color, and mounting location.2 

Brightness will cause impairment if the additional lamp is so bright as to obscure or distract from required lighting. Based on the photographs provided in your submission, it does not appear that your device would cause impairment of a school bus’s required lighting due to brightness. Additionally, because your device is a projection system, brightness concerns, particularly at a distance, are mitigated by the ability to apply a shade to the device to ensure that only the projected image is visible.  

Regarding activation pattern, FMVSS No. 108 requires all auxiliary lamps, with the exception of certain specified types of lamps such as turn signal lamps, to be steady burning.3 You state that the “Focused Illuminated Projection” is “statically illuminating” 

2 Letter to Paul Schaye (September 9, 2019), available at https://isearch.nhtsa.gov/files/571.108%20--%20AMA%20--%20Schaye--front%20color%20changing%20light.htm. 
3 Prior to 2007, FMVSS No. 108 included an explicit requirement that, with the exception of certain types of required lamps (e.g., turn signal lamps), all lamps on a vehicle, including auxiliary lamps, must be steady burning. In 2007, NHTSA implemented an administrative reorganization of FMVSS No. 108 which, among other things, converted the blanket steady burning requirement (and its exceptions) into individual activation requirements for each type of required lamp. See 72 FR 68234 (Dec. 4, 2007). Although the reorganized rule no longer includes a blanket steady burning requirement, NHTSA stated in the preamble to the reorganized rule that its rewrite of FMVSS No. 108 is considered administrative in nature because the standard’s existing requirements and obligations are not being increased, decreased, or substantively modified. Moreover, NHTSA continues to believe that flashing auxiliary lamps would impair the effectiveness of required lamps by distracting or confusing other road users. See Id., at FN 7. 

Page 3
Mr. Bobby Lanyon 

the stopping threshold in front of and behind the bus, which we understand to mean that the device is steady burning. Therefore, your device’s activation pattern is unlikely to distract other road users from the required lighting and will not impair the effectiveness of the vehicle’s required lighting due to activation pattern. 

Regarding color, NHTSA has stated that impairment concerns prohibit the use of lamps of colors that are likely to cause confusion to other road users.4 For example, NHTSA has previously stated that red lamps placed on the front of non-school-bus vehicles impair the effectiveness of lighting required under FMVSS No. 108 because drivers understand red to mean stop and those lamps can be confused with stop lamps.5 However, this is not necessarily the case with school buses because they are required to have red signal warning lamps on the front of their cabs. Here, the question is whether your device would impair a school bus’s required lighting, in particular the red signal warning lamps that are required on the front and rear of school buses. The purpose of the signal warning lamp is to “identify a vehicle as a school bus and to inform other users of the highway that such vehicle is stopped on the highway to take on or discharge school children.”6 Your device is designed to increase the conspicuity of a stopped school bus and benefit that purpose. It supplements the signal warning lamp by activating only while the required red signal lamp is activated, which occurs when the bus is in a stopped and loading/unloading state. This matches the purpose of the red signal lighting. In addition, nearby drivers are likely to understand the red indicator to mean “stop” and “do not enter the projected zone,” which may further the purpose of the required signal lamps. Therefore, it is our opinion that it is unlikely to impair the effectiveness of lamps required by FMVSS No. 108 due to color. 

Regarding mounting location, lamps impair the effectiveness of required lighting under FMVSS No. 108 if they are mounted in locations that cause them to interfere with the ability of a vehicle’s required lamps to achieve their purpose.7 Generally, we have found that this requires auxiliary lighting to be mounted “far enough away” from other lamps that it does not impair their effectiveness.8 Although your device is mounted adjacent to or just below the signal warning lamps, your device’s mounting location is not likely to impair the signal warning lamps because your device is a projection system. At distance, especially if there is a shade on the device, other road users are unlikely to observe any interference with the signal lamp. 

Previously, we have found that certain auxiliary stop signal lamps on school buses were likely to impair the effectiveness of required lighting under FMVSS No. 108. For example, we found the ALLSTOP system, a red flashing light affixed to the roof of a 

4 Letter to Paul Schaye (September 9, 2019), available at https://isearch.nhtsa.gov/files/571.108%20--%20AMA%20--%20Schaye--front%20color%20changing%20light.htm. 
5 Id.
6 49 CFR 571.108 S4.
7 Letter to Paul Schaye (September 9, 2019), available at https://isearch.nhtsa.gov/files/571.108%20--%20AMA%20--%20Schaye--front%20color%20changing%20light.htm.  
8 See, e.g., Letter to Redacted (January 21, 2004), available at
https://isearch.nhtsa.gov/files/GF007705.html. 
 

Page 4
Mr. Bobby Lanyon 

school bus that only activated when the school bus door was open, “would divert a
driver’s attention from the required signal lamps and cause confusion with respect to their meaning….”9 Your device is distinguishable from the ALLSTOP and is unlikely to cause confusion with the signal warning lamp for two reasons: first, it is steady burning, and second, the meaning of your device’s signal appears to be unambiguous. The ALLSTOP had a much higher likelihood of distracting or confusing drivers because it was a flashing and rotating device like a police light. NHTSA has found impairment where it is likely that an auxiliary or alternative lighting scheme could confuse drivers due to an ambiguous meaning.10 For example, NHTSA recently stated that the HELP system, which flashed the turn signal lamps to create an additional hazard warning system, had an ambiguous meaning if used in any situation other than while parked.11 Your device, however, as two static projected red lines on the road, plainly indicates “do not enter.” Therefore, it is our opinion that your device is unlikely to impair the effectiveness of the required lighting under FMVSS No. 108 and is permissible under that standard.  

With respect to the aftermarket, 49 U.S.C. 30122 has the effect of requiring that the installation of any aftermarket vehicle lamp, by a manufacturer, distributor, dealer, or motor vehicle repair business, must not “make inoperative” any element of design or device installed on a vehicle in accordance with FMVSS No. 108. As with original equipment, we regard the addition of a projection lamp that is used in the way we understand your “Focused Illuminated Projection” system to operate not to make inoperative a vehicle’s original required lighting equipment. 

If you have further questions, please contact Eli Wachtel of my staff at (202) 366-2992. 

Sincerely, 

John Donaldson
Acting Chief Counsel
 

9 Letter to J. Adam Krugh (May 22, 2003), available at https://isearch.nhtsa.gov/files/002769drn.html. 
10 Letter to Steven T. Powers (January 19, 2021), available at https://isearch.nhtsa.gov/files/571.108--HELP%20System--Powers.htm. 
11 Id. 

Dated: 3/21/23
Ref: Standard No. 131

ID: NCC-220915-001 Speedometer Conformity Interp Letter

March 21, 2023

Chris Cowen
Port Intelligence Officer
Customs and Border Protection Tactical Operations
104 Bridge Approach Plaza
Ogdensburg, NY 13669 

Dear Mr. Cowen: 

This responds to your email to the National Highway Traffic Safety Administration (NHTSA) requesting a determination as to whether certain vehicles imported into the United States from Canada comply with applicable Federal Motor Vehicle Safety Standards (FMVSS) relating to speedometers. Specifically, you ask whether vehicles equipped with both an analog speedometer that displays only in kilometers per hour (km/h) and a multifunction display that is capable of displaying in miles per hour (MPH) if the driver selects that option would be permissible for importation into the United States without modification. 

Based on the requirements of FMVSS No. 101, Controls and displays, the answer is no. These vehicles do not conform to NHTSA’s requirements and thus are not eligible for importation without modification. Please note that our answer is based on our understanding of the specific information provided in your email. 

Background 

The National Traffic and Motor Vehicle Safety Act of 1966 (Safety Act, 49 U.S.C. Chapter 301) authorizes NHTSA to issue safety standards applicable to motor vehicles and items of motor vehicle equipment. However, NHTSA does not approve motor vehicles or motor vehicle equipment. Instead, the Safety Act establishes a self certification process under which each manufacturer is responsible for certifying that its products meet our safety standards. This agency periodically tests vehicles and equipment items for compliance with the standards and investigates alleged safety-related defects. 

Page 2
Mr. Chris Cowen 

Of relevance to your request, NHTSA issued Federal Motor Vehicle Safety Standard No. 101 (49 CFR § 571.101), which primarily ensures the accessibility, visibility, and recognition of motor vehicle indicators, including speedometers, to reduce safety hazards caused by diversion of the driver’s attention. This standard specifies performance requirements for location, identification, color, and illumination of motor vehicle indicators. It applies to passenger cars, multipurpose passenger vehicles, trucks, and buses. 

Discussion 

The questions inherent in your request, as we understand it, are below:  

1. Do the speedometers meet the FMVSS No. 101 definition of an indicator?  
2. If so, does each indicator meet the requirements of FMVSS No. 101? 

Regarding the first question, paragraph S4 of FMVSS No. 101 defines an indicator as “a device that shows the magnitude of the physical characteristics that the instrument is designed to sense.”  Table 1 of FMVSS No. 101 specifies that speedometers are, in fact, indicators. 

Regarding the second question, paragraph S5 of FMVSS No. 101 states that all covered vehicles fitted with indicators listed in Table 1 must meet the requirements for the location, identification, color, and illumination of those indicators. 

Based on our review of the photographs you provided, the speedometers at issue appear to satisfy the requirements for location and color, in accordance with paragraph S5.1 “Location” and paragraph S5.4 “Color.”  

We now turn to the identification requirement. Table 1 specifies that speedometers must be identified with units of measurement, using either “MPH” or “MPH and km/h.” You provided pictures of two speedometers: an analog gauge displaying only metric units (km/h) and a digital display that allows the driver to select U.S. customary units (MPH). The analog gauge clearly does not meet the identification requirement of Table 1 because it is marked only in km/h. Next, we consider whether the digital display, defined as a multi-task display in paragraph S4 of FMVSS No. 101, meets the requirement. A multi task display is a display on which more than one message can be shown simultaneously. For example, the display here reportedly presents a layered menu of functions that the driver can change. If the driver selects the digital “MPH” display, the speedometer appears to meet the requirements of FMVSS No. 101. If, however, the driver selects a different menu option (or no menu option), the speedometer no longer displays “MPH.” Therefore, the multi-task display, by itself, does not meet the identification requirement that “MPH” always be displayed, and in the absence of an analog speedometer that displays MPH, this vehicle would not be compliant with FMVSS No. 101.  

We have not evaluated the “illumination” requirement, as your correspondence does not provide sufficient information to allow us to do so. 

Page 3
Mr. Chris Cowen 

In sum, an indicator, including a speedometer, must meet all requirements of FMVSS No. 101. For the reasons enumerated above, the requirements of the FMVSS are not met and the vehicles are noncompliant. Therefore, vehicles containing these instruments are not eligible for importation into the United States without modification. 

I hope this information is helpful. If you have any further questions, please feel free to contact Terrence Sommers of my staff at this address or at terrence.sommers@dot.gov.  

Sincerely,

John Donaldson
Acting Chief Counsel

Dated: 3/23/23
Ref: Standard No. 101

ID: NCC-230816-001 Antolin Sun Visor

May 17, 2024

Dr. Enrique Curiel Sanz
Passive Safety Manager – Engineering Shared Services
Grupo Antolin
Enrique.curiel@grupoantolin.com 

Dr. Curiel Sanz, 

This responds to your email to the National Highway Traffic Safety Administration (NHTSA) concerning the standards that sun visors must meet under the Federal Motor Vehicle Safety Standards (FMVSS). Your question concerns evaluation of sun visors, specifically how NHTSA determines if the sun visor is covered in an energy absorbing material. Please note that our answer below is based on our understanding of the specific information provided in your email. 

Background 

NHTSA is authorized by the National Traffic and Motor Vehicle Safety Act (Safety Act, 49 U.S.C. Chapter 301) to issue federal motor vehicle safety standards (FMVSS) that set performance requirements for new motor vehicles and new items of motor vehicle equipment. The Safety Act requires manufacturers to self-certify that their vehicles and equipment conform to all applicable FMVSS in effect on the date of manufacture. NHTSA also investigates safety-related defects. 

In your July 19, 2023 message, you asked about the evaluation criteria for sun visors. Specifically, you asked whether sun visors are tested with a pendulum to determine if they are made of an energy absorbing material, and if so, which criteria are used to determine whether the sun visor passes or fails the test. On July 24, 2023, NHTSA responded to your message, indicating that the sun visor requirements in FMVSS No. 201 require that the visor be constructed of or covered with energy absorbing material and that each sun visor mounting present no rigid material edge radius of less than 3.2 mm that is statically contractable by a spherical 165 mm diameter head form. Thereafter, you requested clarification as to how a manufacturer may confirm that a visor’s material meets the definition of “energy-absorbing,” such as material composition or testing under impact conditions. 

Discussion 

As explained, under the Safety Act, each manufacturer of a motor vehicle or item of motor vehicle equipment is responsible for certifying that its products meet all applicable safety standards. Given
 

1 49 U.S.C. 30115. 

Page 2 

Dr. Enrique Curiel Sanz 

this “self-certification” regime, NHTSA does not certify or approve motor vehicles or motor vehicle equipment for compliance with the FMVSS. Manufacturers may not certify a vehicle or item of motor vehicle equipment if, “in exercising reasonable care, [they have] reason to know the certificate is false or misleading in a material respect.”
2 

FMVSS No. 201, “Occupant protection in interior impact,”3 establishes performance requirements designed to reduce the risk of injury in the event an occupant strikes the interior of a vehicle during a crash. Paragraph S5.4 of the standard requires that sun visors be “constructed of or covered with energy-absorbing material” and that the visor’s mounting must “present no rigid material edge radius of less than 3.2 mm that is statically contactable by a spherical 165 mm head form.” The purpose of this requirement is to reduce the injuries that occur when occupants strike the visor or visor mounting with their heads.  

The standard does not further define “energy-absorbing.” Moreover, neither the standard nor NHTSA’s own test procedure4 provides a performance-based or material definition of energy-absorbing, or a test for measuring the energy-absorption capability of sun visor material. Further, the laboratory test procedure for assuring compliance with the standard requires only that the sun visor be made of an energy-absorbing material; no further guidance is provided. Therefore, the responsibility is with the manufacturer to self-certify that the material from which sun visors are constructed or with which they are covered is energy-absorbing to meet the requirements of this standard. 

In so doing, please note that in addition to meeting the S5.4 requirements, S4.2 dictates that vehicles must also comply with the requirements of S6. S6.1.4.2 in turn requires that new vehicles meet the performance standards set forth in S7. Therefore, in addition to the requirement that sun visors be constructed of or covered in an energy absorbing material, manufacturers of sun visors must construct them in such a manner as to ensure compliance with the performance standard of S7 when installed in a vehicle. Compliance with S7 will ensure that the sun visors meet the performance standard, which is what NHTSA requires, along with ensuring that all components are free of safety defects. 

I hope this information is helpful. If you have any further questions, please feel free to contact Terrence Sommers of my staff at the address above or at (202) 366-7577. 

Sincerely,
Adam Raviv
Chief Counsel
 

2 Id.
3 Available at https://www.govinfo.gov/content/pkg/CFR-2022-title49-vol6/pdf/CFR-2022-title49-vol6-sec571-201.pdf (last accessed May 16, 2024).
4 Available at https://www.nhtsa.gov/sites/nhtsa.gov/files/documents/tp-201-02a_tag.pdf (last accessed May 16, 2024).

Dated: 5/17/24
Ref: Standard No. 201

ID: Interpretation-ElectraMeccanica-May 22 2024

May 22, 2024

Mr. Isaac Moss
Chief Administration Officer
ElectraMeccanica
EMV Automotive USA, Inc.
11647 Ventura Blvd.
Studio City, CA 91604 

Dear Mr. Moss: 

This letter responds to your request, on behalf of the ElectraMeccanica Automotive USA, Inc., for guidance as to whether passenger car tires certified to meet Federal Motor Vehicle Safety Standard (FMVSS) No. 139 may be installed on new motorcycles. 

Your letter references a December 30, 1982 interpretation letter confirming that paragraph S5.1.1 of FMVSS No. 120 permitted a motorcycle to be equipped with passenger tires certified as complying with FMVSS No. 109, as long as the tires were fitted to rims listed as suitable for use with the equipped tires, and as long as those rims met the marking requirements of FMVSS No. 120.1 You note that since this 1982 interpretation letter, FMVSS No. 120 has been revised. Although you do not note this in your letter, since 1982, the National Highway Traffic Safety Administration (NHTSA) has substantially updated tire requirements and new passenger car tires are now required to meet FMVSS No. 139. You ask three questions in your letter, and I will address each in turn. 

First, you ask whether NHTSA can expand its December 30, 1982 interpretation letter to include passenger cars meeting the requirements of FMVSS No. 139. I can confirm for you that FMVSS No. 120 allows new motorcycles to be equipped with tires certified to meet FMVSS No. 139. This is explicitly stated in paragraph S5.1.1 of FMVSS No. 120. 

Second, you ask whether NHTSA can confirm that NHTSA would reference S4 of FMVSS No. 139, in lieu of the references to S4.4 of FMVSS No. 109 and S5.1 of FMVSS No. 119 

1 Letter to Anonymous (Confidential) (Dec. 30, 1982), available at https://www.nhtsa.gov/interpretations/1982-337  

Page 2
Mr. Isaac Moss 

contained in S5.1.1 of FMVSS No. 120. The answer to this question is yes. If tires certified to meet FMVSS No. 139 are installed on a new motorcycle, the tire manufacturer must list the rims as suitable for use with those tires in accordance with S4 of FMVSS No. 139. This requirement is consistent with the tire and rim matching information for tires certified with FMVSS Nos. 109 or 119. S4 of FMVSS No. 139, like S4.4 of FMVSS No. 109 and S5.1 of FMVSS No. 119, provides for disclosure of the rims that may be used with each tire a manufacturer produces. The tire’s manufacturer may make this disclosure either in a specific document provided to dealers of the manufacturers’ tires and to NHTSA, or in a yearbook published by one of several tire and rim standards organizations. 

Third, you ask whether NHTSA can provide guidance on whether compliance with FMVSS No. 110 is required in addition to FMVSS No. 120 when tires certified to meet FMVSS No. 139 are used on motorcycles. The answer to this question is no. FMVSS No. 110 is not applicable to motorcycles, even if tires meeting FMVSS No. 139 are installed on motorcycles. S2 of FMVSS No. 110 explicitly excludes motorcycles from the applicability of FMVSS No. 110. The only tire selection and rim standard applicable to motorcycles is in FMVSS No. 120. 

I hope this information is helpful. If you have any further questions, please feel free to contact David Jasinski of my office at (202) 366-2992. 

Sincerely,
Adam Raviv
Chief Counsel

Dated: 5/22/24
Ref: Standard No. 139

ID: NCC-211019-002 Zorn VW EPB FMVSS 135 2024.05.31_Interp

May 31, 2024

Mr. Thomas Zorn 

Vice President 

Vehicle Safety Office 

Volkswagen Group of America 

2200 Woodland Pointe Ave. 

Herndon, VA 20171 

Dear Mr. Zorn: 

This interpretation responds to your letter asking whether Volkswagen’s new Electronic Parking Brake (EPB) system complies with Federal Motor Vehicle Safety Standard (FMVSS) No. 135, Light vehicle brake systems. Specifically, you asked (1) whether paragraph S5.2 of FMVSS No. 135 would permit an EPB system that uses a traditional friction brake combined with a mechanical drivetrain lock; and (2) whether Volkswagen may rely on the entire EPB system for compliance with the test set out in paragraph S7.12. Based on the information you have provided, our answer to both of your questions is yes. 

By way of background information, the National Highway Traffic Safety Administration (NHTSA) does not provide advance approvals of motor vehicles or motor vehicle equipment. Under 49 U.S.C. Chapter 301, manufacturers are required to ensure that their vehicles and equipment meet applicable requirements. The following represents our opinion based on the facts provided in your letter. 

In addition, in responding to this request, NHTSA notes that the contents of this letter do not have the force and effect of law and are not meant to bind the public in any way. This letter is only intended to provide clarity regarding existing requirements under the law at the time of signature. 

Paragraph S5.2 of FMVSS No. 135 provides: “Each vehicle shall be equipped with a parking brake system of a friction type with solely mechanical means to retain engagement.” The term “parking brake” is defined in 49 C.F.R. Part 571.3(c) as “a mechanism designed to prevent the movement of a stationary motor vehicle.” Thus, a compliant parking brake must prevent movement of a stationary motor vehicle by means of friction. Additionally, the parking brake system must also have “solely mechanical means to retain engagement,” meaning it cannot be held in place by non-mechanical means such as fluid, air, or electricity. 

Paragraph S7.12.2 of FMVSS No. 135 describes NHTSA’s conditions and procedures for testing whether a parking brake system complies with our standard. The test procedures require a test conductor to, among other things, drive the vehicle onto a 20 percent grade, apply the 

Mr. Thomas Zorn 

Page 2 

service brake with enough force to hold the vehicle stationary, shift the transmission into neutral, engage the parking brake system, and remove all force from the service brake. After the test conductor has taken the above steps, the vehicle must then remain stationary for five minutes. If the vehicle remains stationary for the required five minutes, the test conductor then repeats the test with the vehicle facing in the opposite direction on the grade. If the vehicle once again meets the stationary time requirement, and meets all other requirements in the paragraph, the parking brake system passes the compliance test.  

The EPB system described in your letter appears to be a parking brake of a friction type with solely mechanical means to retain engagement. You describe Volkswagen’s new EPB as a system that will “utilize a traditional friction brake combined with a mechanical lock that is automatically engaged in the vehicle drivetrain when the EPB is activated.” Based on this description, the system has a friction element combined with a mechanical drivetrain lock designed to hold the vehicle stationary. Additionally, based on the information provided in your letter, engagement of the friction element of the EPB is not retained by pneumatic or hydraulic means. To the best of our knowledge, the only ways to retain engagement of a friction type brake are by pneumatic, hydraulic, or mechanical means. Because your friction brake is not retained by pneumatic or hydraulic means, for the sake of this letter, we are assuming that engagement of the friction element of the EPB is retained by mechanical means.1 Applying that assumption, the Volkswagen EPB system described in your letter appears to meet the requirements of S5.2 of FMVSS No. 135. 2 

You also state that Volkswagen intends to rely on the entire EPB system to demonstrate compliance with paragraph S7.12 and ask whether NHTSA would conduct its compliance tests similarly. In conducting compliance testing for parking brakes, NHTSA follows the testing procedures set out in S7.12, as described above. You state that the friction element and mechanical lock are “designed to operate together only, and cannot be engaged individually by the vehicle operator.” Additionally, you indicate that it would be impossible for Volkswagen’s EPB system to engage the friction brake exclusively without the mechanical lock engaging. The testing procedure specified in S7.12 does not mandate a parking brake system hold a vehicle stationary by exclusively friction means. Accordingly, if NHTSA conducted compliance testing on the EPB described in your letter, it would follow the procedures as written in S7.12. 

I hope this answers your questions. If you have any further questions regarding this matter, please feel free to contact Mr. Matthew Filpi of my staff at (202) 366-2992. 

Sincerely,

ADAM RAVIV
Adam Raviv Chief Counsel

Dated: 5/31/24
Ref: Standard No. 135

ID: NCC-230927-001 FMVSS 135 - Telltale_ St. Pierre_ Canoo

June 7, 2024

Mr. Barry St. Pierre 

Sr. Homologation Engineer  

Canoo 

19951 Mariner Ave 

Torrance, CA 90503 

barry.st.pierre@canoo.com

Dear Mr. St. Pierre: 

I write in response to your September 12, 2023 email to the National Highway Traffic Safety Administration (NHTSA) asking for information on federal requirements for telltales in light vehicle brake systems. Please note that our answer below is based on our understanding of the specific information provided in your email correspondence. 

In responding to this request, NHTSA notes that the contents of this letter do not have the force and effect of law and are not meant to bind the public in any way. This letter is only intended to provide clarity regarding existing requirements under the law at the time of signature. 

Background 

NHTSA is authorized by the National Traffic and Motor Vehicle Safety Act (Safety Act, 49 U.S.C. Chapter 301) to issue Federal Motor Vehicle Safety Standards (FMVSS) setting performance requirements for new motor vehicles and new items of motor vehicle equipment. The Safety Act requires manufacturers to self-certify that their vehicles and equipment conform to all applicable FMVSS in effect on the date of manufacture. NHTSA also investigates safety-related defects. 

Your email correspondence seeks clarification of the requirement in 49 CFR § 571.135 S5.5.5(a) that visual indicators “shall have letters not less than 3.2mm (⅛ inch) high.” You state correctly that, if the telltale is the word “BRAKE,” it must meet the height requirement. You also ask about the specific proposed brake and ABS icon symbols pictured in your correspondence. In particular, you ask: (1) if a brake symbol includes the letter “P” as part of the symbol, whether it is sufficient for the symbol as a whole to meet the 3.2 mm height requirement of S5.5.5(a), or whether the letter “P” by itself must meet the height requirement; and (2) if an antilock braking system symbol includes the letters “ABS” as part of the symbol, whether it is sufficient for the symbol as a whole to meet the 3.2 mm high requirement, or whether the letters “ABS” by themselves must meet the height requirement. 

Discussion 

As you acknowledge in your correspondence, 49 CFR § 571.135 (FMVSS 135) S5.5.5(a) specifies labeling requirements for light vehicle brake systems. It states: 

Each visual indicator shall display a word or words in accordance with the requirements of Standard No. 101 (49 CFR 571.101) and this section, which shall be legible to the driver under all daytime and nighttime conditions when activated.
Unless otherwise specified, the words shall have letters not less than 3.2 mm (⅛ inch) high and the letters and background shall be of contrasting colors, one of which is red. Words or symbols in addition to those required by Standard No. 101 and this section may be provided for purposes of clarity. 

49 CFR § 571.101 (FMVSS 101), in turn, includes requirements for telltales and indicators. Section 5.2.1 states, in relevant part: 

[E]ach control, telltale and indicator that is listed in column 1 of Table 1 or Table 2 must be identified by the symbol specified for it in column 2 or the word or abbreviation specified for it in column 3 of Table 1 or Table 2. If a symbol is used, each symbol provided pursuant to this paragraph must be substantially similar in form to the symbol as it appears in Table 1 or Table 2. 

Table 1 of FMVSS 101 shows the required telltales for the items for which you request clarification: brake system malfunction and anti-lock brake system malfunction. These telltales have specific words or abbreviations that must be used as identifiers. Specifically, the word “Brake” must be used to indicate brake system malfunction. The words “Antilock” or “Anti-lock,” or the abbreviation “ABS,” must be used to indicate antilock brake system malfunction for vehicles subject to FMVSS Nos. 105 or 135. Unlike certain other items, Table 1 of FMVSS 101 does not permit the use of a symbol as an alternative to words or abbreviations to indicate either a brake system malfunction or an anti-lock brake system malfunction. Further, these required words or abbreviations must comply with the 3.2 mm height requirement of FMVSS 135 S5.5.5(a). 

NHTSA understands the symbols proposed in your correspondence to be separate from and additional to the required words or abbreviations discussed above. With this understanding, the two proposed symbols pictured in your correspondence would not be subject to the word height requirement laid out in FMVSS 135 S5.5.5(a), as they would be considered additional words or symbols used for clarification purposes. Accordingly, neither the symbols, nor the letters that are part of the symbols, would be required to be at least 3.2 mm. 

However, if a vehicle does not use Table 1’s required words or abbreviations as a telltale for the item in question, and instead only uses a symbol that does not contain the required words or abbreviations, then the vehicle does not meet the requirements of FMVSS 101 S5.2.1, regardless of the height of the symbol or the letter(s) in the symbol. 

Finally, we note that, as discussed above, one permissible telltale for an anti-lock brake system malfunction is the abbreviation “ABS.” Accordingly, if the symbol pictured in your letter that includes the letters “ABS” is the only telltale used in a vehicle to indicate an antilock system brake malfunction, then the letters “ABS” in that symbol must meet the 3.2 mm minimum height requirement in FMVSS 135 S5.5.5(a). It would not be sufficient for the symbol as a whole to meet this height requirement, because S5.5.5(a) specifically requires the “words” to meet the requirement. 

I hope this information is helpful. If you have any further questions, please feel free to contact Natasha Reed of my staff at this address or at (202) 366-2992.

Sincerely,
Adam Raviv
Chief Counsel

Dated: 6/7/24
Ref: Standard No. 135

ID: NCC-231121-001 Autoliv (Veoneer) Spotlight Interpretation 1

June 27, 2024

Richard Seoane 

VP Operations and Business Development 

Thermal Product Area 

Veoneer 

420 South Fairview Avenue Goleta, CA 93117 

Dear Mr. Seoane: 

This responds to your request dated October 10, 2016, concerning the application of Federal Motor Vehicle Safety Standard (“FMVSS”) No. 108, Lamps, reflective devices, and associated equipment, to a lighting system you describe in your letter. As I explain below, based on your description of the system we agree that it is supplemental lighting, but disagree with your assertion that it would not impair the effectiveness of any of the required lighting equipment. 

In responding to this request, the National Highway Traffic Safety Administration (NHTSA) notes that the contents of this letter do not have the force and effect of law and are not meant to bind the public in any way. This letter is only intended to provide clarity regarding existing requirements under the law at the time of signature. 

Description of the Marking Light and the Request for Interpretation 

In your letter, you request an interpretation of FMVSS No. 108 as applied to an auxiliary light designed to prevent nighttime crashes (the Marking Light). As you describe it, the Marking Light consists of two auxiliary spotlights operated independently of the headlighting system. The spotlights are mounted symmetrically about the vertical centerline of the vehicle, below the headlamps, and pointed down at a fixed angle. The Marking Light operates independently of the upper and lower beam headlamps to produce a narrow, white-light beam pointed down to highlight the path to an object (such as a pedestrian) in or near the forward roadway so that the driver can see it. The Marking Light is activated and controlled by Autoliv’s Night Vision System, which has an infrared camera that detects pedestrian, bicyclist, and animal hazards up to 100 meters in front of the vehicle. The Night Vision System alerts the driver with in-vehicle 

Page 2
Richard Seoane 

visual (e.g., head-up display icon and/or dash icon) and audible signals indicating activation of the Marking Light and directs the Marking Light to illuminate the path over the ground to the hazard to visually alert the driver of the presence and location of the hazard. The system does not engage vehicle steering or brakes. The Marking Light cannot be activated manually by the driver or continuously operated; it is activated only by the night vision system when a hazard is detected to assist the driver in seeing the hazard but does not assist the driver in seeing the roadway. You state that the Marking Light is disabled in the presence of oncoming and preceding traffic so that it does not glare drivers on a wet or shiny roadway. 

You explain your position that the Marking Light is a supplemental lamp, not a required lamp such as a headlamp. You then make a variety of different arguments (and provide data) to support your view that the Marking Light does not impair the effectiveness of any of the required lighting. We summarize these arguments in more detail where relevant in the discussion below. 

Applicable Requirements 

FMVSS No. 108, which is codified at 49 C.F.R. § 571.108, sets requirements for vehicle lighting. The standard requires a variety of types of lighting, depending on vehicle type and size, and specifies requirements for these required lighting elements. The standard also sets requirements (referred to as “if equipped” requirements) for some non-mandatory lighting devices, such as daytime running lamps. 

Lighting devices that FMVSS No. 108 does not require or regulate as “if equipped” lighting devices are considered supplemental (or auxiliary) lighting devices. Supplemental lighting is generally permitted as long as it does not impair the effectiveness of any of the lighting equipment required by the standard. See FMVSS No. 108 S6.2.1 (also referred to as the “impairment” provision). 

FMVSS No. 108 applies only to original equipment and lighting equipment manufactured to replace original lighting equipment required by FMVSS No. 108. The standard does not directly apply to supplemental lighting devices sold in the aftermarket. Instead, supplemental lighting offered as an aftermarket accessory is subject to the “make inoperative” prohibition (49 U.S.C. § 301222), which prohibits certain specified commercial entities (such as dealers or repair shops) from taking a vehicle out of compliance with an FMVSS. In applying the “make inoperative” prohibition to aftermarket accessory lighting, NHTSA typically asks whether the accessory lighting would impair the effectiveness of any required lighting. Generally, if an item of accessory lighting would not be permitted as original equipment, commercial entities will not be permitted to install the lighting as an aftermarket accessory for a vehicle in use. 

While the vehicle manufacturer has the legal responsibility under the National Traffic and Motor Vehicle Safety Act (Safety Act) to certify that the vehicle complies with FMVSS No. 108 and all other applicable FMVSS, as a practical matter, vehicle manufacturers generally insist that equipment manufacturers provide assurance that their products meet federal standards. The judgment of impairment is one made, in the first instance, by the person installing the device. That decision, however, may be questioned by NHTSA if it appears clearly erroneous. 

Page 3
Richard Seoane 

Discussion 

The threshold issue presented by your request is whether the Marking Light is part of the required headlighting system and thus subject to the requirements applicable to headlighting systems, or supplemental lighting that is regulated by FMVSS No. 108’s impairment provision. We agree with you that the Marking Light would be considered supplemental lighting. 

FMVSS No. 108 requires vehicles to be equipped with one of several permissible headlighting systems.1 Headlighting systems are comprised of headlamps and associated hardware. The purpose of headlamps is primarily to provide forward illumination.2 In determining whether lighting equipment that provides forward illumination is part of the required headlighting system or supplemental lighting, NHTSA looks at several factors. These factors have included, among other things: (1) where the lamp directs its light; (2) whether it uses a headlamp replaceable light source to emit a beam that provides significantly more light flux than supplemental cornering lamps or fog lamps; (3) whether the lamp is intended to be used regularly, or is limited to more narrow driving conditions and situations; or (4) whether there is a manual on/off switch.3 

None of our previous interpretations appear to have addressed a frontal lighting concept precisely like the Marking Light. We agree with you, based on the information you have provided us, that it is supplemental lighting because it is not intended to be used regularly, but is instead a narrow beam that is activated only when there is a hazard forward of the vehicle such as a pedestrian or animal near the roadway. 

Because the Marking Light would be considered supplemental lighting, it is permitted as long as it does not impair the effectiveness of any lighting equipment required by the standard. In its previous interpretation letters, NHTSA has identified a number of different ways that a supplemental lamp could impair the effectiveness of the required lighting.4 

With respect to the Marking Light, there are two types of impairment that are potentially relevant. One is the potential to confuse other drivers arising from the Marking Light’s color, location, or activation pattern.5 The other potentially relevant type of impairment is the potential for glare to other road users due to the intensity of the Marking Light. We address each of these potential types of impairment below. 

1 FMVSS No. 108 Table I-a; S10.
2 FMVSS No. 108 S4 (“Headlamp means a lighting device providing an upper and/or a lower beam used for providing illumination forward of the vehicle.”).
3 See Letter from Jacqueline Glassman, Chief Counsel, to [Redacted] (Jan. 21, 2004). Prior to the 2004 interpretation letter, NHTSA issued several interpretations concerning auxiliary driving beams in which the agency treated those lamps as supplemental lighting without expressly considering the issue. See, e.g., Letter from Erika Z. Jones, Chief Counsel, to P. Soardo, Instituto Elettrotecnico Nazionale (May 22, 1987). If the lamps in question in those earlier interpretations would be considered supplemental lighting under the factors set forth in the 2004 interpretation, they may be consistent with that later interpretation. There is not, however, sufficient information about the lighting systems at issue in those earlier interpretation letters to allow application of the factors from the 2004 interpretation. In any case, the 2004 interpretation has been, to date, NHTSA’s view of the issue.
4 See, e.g., Letter from Jonathan Morrison, Chief Counsel, to Paul Schaye, Pedestrian Safety Solutions (Sept. 9, 2019).
5 See id. 

Page 4
Richard Seoane 

Color and Location 

The impairment provision prohibits auxiliary lamp colors that are likely to confuse other road users.6 For auxiliary lamps located on the front of the vehicle, colors that could cause confusion include red (which could be confused with a tail lamp), green (which could be confused with a traffic signal), and blue (which could be confused with a law enforcement vehicle).7 

You state that because the Marking Light is white, it cannot be confused with a turn signal and would not conflict with the emergency (hazard) lamps or parking lamps. 

We agree that because the Marking Light is white and mounted below the headlamps, it would not likely be confused with the front turn signal (which is amber8) and would not conflict with the vehicle hazard warning (which consists of all required turn signal lamps flashing simultaneously9) or the parking lamps (which must be white or amber10). I therefore agree that the color and location of the Marking Light would not cause confusion with the vehicle’s signal lamps. 

Activation Pattern 

FMVSS No. 108 requires that all auxiliary lamps be steady burning except for auxiliary lamps that supplement required lamps that flash, such as turn signals.11 This requirement means that the lamp must be steady burning when activated, not that it is prohibited from being activated or deactivated automatically.12 However, the (de)activation of the lamp cannot be so frequent or random that the lamp would distract or confuse other road users. For example, a lamp that activates and deactivates on an extremely short time interval due to sensitivity to slight changes in conditions would not be considered steady-burning.13 NHTSA has also interpreted the steady- 

6 Id.
7 Id.
8 FMVSS No. 108 Table I-a.
9 Id. S6.6.2; S4 (definition of vehicle hazard warning signal flasher).
10 Id. Table I-a.
11 See, e.g., Letter from Jonathan Morrison, Chief Counsel, to Paul Schaye, Pedestrian Safety Solutions (Sept. 9, 2019); Letter from Anthony Cooke, Chief Counsel, to Kerry Legg, New Flyer, Inc. (Feb. 21, 2008). Before 2007, FMVSS No. 108 included an explicit requirement that, with certain exceptions (e.g., turn signal lamps), all lamps on a vehicle, including auxiliary lamps, must be steady burning. In 2007, NHTSA implemented an administrative rewrite of FMVSS No. 108 which, among other things, converted the blanket “steady burning” requirement (and its exceptions) into individual activation requirements for each type of required lamp. See 72 FR 68234 (Dec. 4, 2007). Although the reorganized rule no longer includes a blanket “steady burning” requirement, NHTSA stated in the preamble to the reorganized rule that its “rewrite of FMVSS No. 108 is considered administrative in nature because the standard’s existing requirements and obligations are not being increased, decreased, or substantively modified.” Id. Moreover, NHTSA continues to believe that flashing auxiliary lamps would impair the effectiveness of required lamps by distracting or confusing other road users.
12 See Letter from Jonathan Morrison, Chief Counsel, to Paul Schaye, Pedestrian Safety Solutions (Sept. 9, 2019).
13 See id. 

Page 5
Richard Seoane 

burning requirement to mean that headlamp intensity may modulate, but only if the changes in intensity are not detectable by the human eye.14 

You state that the Marking Light is steady burning in that it does not flash (cycle on and off). You state that the Marking Light is activated when the night vision system identifies a pedestrian, bicyclist, or large animal in or near the forward roadway as a hazard. When the object is no longer deemed a hazard, the night vision system switches off the Marking Light. We also understand that the intensity of the Marking Light does not modulate. 

We agree that, based on the facts represented to us in your letter, the Marking Light is steady burning and would therefore not violate the impairment provision in this respect. This conclusion assumes that the Marking Light does not activate and deactivate frequently (which could confuse or distract other road users) or change intensity while activated in a way that is detectable to the human eye. 

Brightness (Photometric Intensity) 

Supplemental lighting can also impair the effectiveness of the required lighting if it is so intense that it glares other road users15 or, relatedly, masks any of the required signal lighting.16 As a point of reference, we note that FMVSS No. 108 specifies two upper beam (or high beam) maxima, at H-V and 4D-V.17 The magnitude of the specified maxima depends on the type of upper beam system; for the purposes of this letter, we will compare the Marking Light to the highest specified maxima at each test point, which are 75,000 candela (cd) at H-V and 12,000 cd 

14 See, e.g., Letter from Stephen Wood, Acting Chief Counsel, to Kiminori Hyodo, Koito Manufacturing Co., Ltd. (Nov. 5, 2005); Letter from John Womack, Acting Chief Counsel, NHTSA, to Joe De Sousa (Mar. 10, 1994) (stating, in the context of a modulating motorcycle headlamp, that “there is no failure to conform if the modulating light from the lamp is perceived to be a steady beam”).
15 See, e.g., Letter from John Womack, Acting Chief Counsel, to Yoshiaki Matsui, Stanley Elec. Co., Ltd. (Sept. 20, 1995) (fog lamp supplementing lower beam) (“Finally, as a cautionary note, we believe that Stanley should evaluate the glare potential of the headlamp when the fog lamp and lower beam are operating simultaneously, as it is important to safety that oncoming drivers not be distracted or discomforted in the operation of their vehicles.”). Cf. Letter from Jacqueline Glassman, Chief Counsel, to Rusty Riggin, Willow Development (Aug. 2, 2002) (explaining that a supplemental rear cornering lamp could violate the impairment provision if it was so intense that it “create[d] distracting glare”).
16 See, e.g., Letter from Jonathan Morrison, Chief Counsel, to Paul Schaye, Pedestrian Safety Solutions (Sept. 9, 2019) (“NHTSA has in the past stated that auxiliary lamps that were so bright as to ‘mask’ adjacent required turning signal lamps would be prohibited due to impairment.”); Letter From Samuel Dubbin, Chief Counsel, to Richard Russell (Dec. 22, 1995) (“[W]e would regard the vehicle manufacturer’s certification as negated if the brightness and location of the auxiliary lamps were such as to affect an oncoming driver’s ability to perceive the front turn signals.”).
17 FMVSS 108 Table XVIII. The photometry requirements specified in Table XVIII consist of test points at which the intensity of the light is measured. The requirements at each test point consist of minima and/or maxima. The test points are defined with respect to an angular coordinate system relative to the headlamp. Thus, H-V identifies a test point zero degrees up and zero degrees down relative to the headlamp, and 4D-V identifies a test point 4 degrees down relative to the headlamp. See also Letter from Erika Jones, Chief Counsel, to Byung Soh, Target Marketing Systems (Sept. 13, 1988) (“Effectiveness may be impaired if the device creates a noncompliance in the existing lighting equipment or modifies its candlepower to either below the minima or above the maxima permitted by the standard.”); Letter from Erika Jones, Chief Counsel, to George Ziolo (Sept. 12, 1988) (vehicle equipped with two upper beam headlamp systems would violate the impairment provision because it would exceed the upper beam maxima at H-V and 4D-V). 

Page 6
Richard Seoane 

at 4D-V. We consider the upper beam maxima as proper comparators because the Marking Light, like the upper beam, is designed to activate when no other cars are nearby.18 Just as upper beam headlamps are subject to maximum intensity limits, even though they are designed to turn off in the presence of oncoming traffic, the same concerns apply to forward-facing auxiliary lighting. 

You argue in your letter that the Marking Light will not glare other road users or mask any of the required signal lighting. You state that the Marking Light is disabled in the presence of oncoming traffic, so that its downward angle does not glare other drivers on a wet or shiny roadway. You also state that because the Marking Light is low to the ground and produces very little light above the horizontal plane of the headlamps, it cannot glare another driver or pedestrians. You state that because of these features, the Marking Light does not impair an oncoming driver’s ability to perceive the front turn signals. In a meeting with our office, you also indicated that the spotlamps on each side of the vehicle are generally not additive (combined). 

You also provided data on the intensity of the Marking Light (an iso-candela plot) based on on-vehicle measurements at a test laboratory. The photometric testing indicates that the Marking Light’s maximum intensity is 113,440 cd (at approximately four degrees down). You noted that the test setup resulted in higher estimated light intensities than what would be more accurately estimated by a goniometric component test conducted in a properly designed component lamp goniometry facility with appropriate stray light control. 

We believe that the Marking Light would violate the impairment provision because it would exceed—dramatically—the maximum permissible brightness of upper beams at 4D-V. This extreme intensity is a concern even if the Marking Light beam is aimed at a downward angle and the system is designed so that the light is disabled in the presence of oncoming and preceding vehicles, because it could still glare other motorists if the vision system does not correctly detect an oncoming or preceding vehicle and prevent the Marking Light from activating. This glare could happen, for example, if the vehicle crests the top of a hill when another vehicle is approaching, the vehicle encounters another vehicle at an intersection without detecting the other vehicle approaching from the side, or if the Marking Light reflects off wet pavement. 

We recognize that the photometric test setup led to overestimates of the Marking Light’s intensity. Nevertheless, the Marking Light is so intense that a more accurate estimate would likely still greatly exceed the upper beam maximum. We also note that the Marking Light’s intensity dramatically exceeds not only the upper beam maximum at 4D-V (12,000 cd), but also the maximum allowed for any individual upper beam headlamp (75,000 cd at H-V). This intensity presents a risk that other road users could be subject to significant glare. 

Conclusion 

I conclude that the Marking Light would be prohibited by the impairment provision in FMVSS No. 108 with respect to the Marking Light’s intensity at 4D-V.
18 FMVSS No. 108 S4 (upper beam defined as “beam intended primarily for distance illumination and for use when not meeting or closely following other vehicles”). 

Page 7
Richard Seoane 

If you have any further questions, please contact John Piazza of my staff at (202) 366-2992. 

Sincerely,
ADAM RAVIV
Adam Raviv Chief Counsel

Dated: 6/27/24
Ref: Standard No. 108

ID: NCC-240112-Goodyear Tire and Rubber Co.

August 8, 2024

Mark Cherveny
Manager, Global Relations, Standards & Compliance The Goodyear Tire & Rubber Company
200 Innovation Way
Akron, OH 44316-0001 

Dear Mr. Cherveny: 

This letter responds to Goodyear Tire & Rubber Company’s “Letter of Interpretation Request for § 571.139 S5.5(c): maximum inflation pressure,” which states that your company has received requests from original equipment vehicle manufacturers to stamp “350 kPa” on “Extra Load” passenger tires. Your request seeks clarification on whether your company is “permitted to stamp an Extra Load passenger tire with a maximum permissible inflation pressure of 350 kPa.” It then asks: “If this is permitted, then would the minimum breaking energy specified in [49 C.F.R.] § 571.109 Table I-C and the test inflation pressures specified in § 571.109 Table II – Test Inflation Pressures … still apply for strength testing?” 

In responding to this request, the National Highway Traffic Safety Administration (NHTSA) notes that the contents of this letter do not have the force and effect of law and are not meant to bind the public in any way. This letter is only intended to provide clarity regarding existing requirements under the law at the time of signature. 

As to your question whether “Extra Load” tires may be labeled as 350 kPa, NHTSA’s Federal Motor Vehicle Safety Standards (FMVSS) have no labeling requirements based on whether a passenger car tire is extra load or standard load. Thus, the FMVSS do not prohibit the proposed labeling on passenger car tires.1 

As to your question about the minimum breaking energy and inflation pressure tests in FMVSS No. 109, the testing requirements in Table I-C and Table II are based on a tire’s maximum inflation pressure and make no reference to whether the tire is labeled as standard load, extra

1 This letter, like your request, focuses solely on the FMVSS. Whether the proposed labeling complies with any other federal or state law or standards is outside the scope of this letter and we take no position on that question.

Page 2
Mr. Mark Cherveny 

load, or XL.2 Thus, passenger car tires with a maximum inflation pressure of 350 kPa are subject to the inflation pressures indicated for 350 kPa tires in the testing requirements set forth in Tables I-C and II. 

We note that your request did not inquire how the testing requirements in FMVSS 139, as opposed to those in FMVSS 109, apply to 350 kPa tires that have been stamped “Extra Load.” Because you did not request an interpretation of the testing standards in FMVSS 139, this letter does not provide such an interpretation. 

Finally, as you note in your letter, FMVSS No. 138—unlike FMVSS 109 and 139—does refer to the maximum inflation pressures for both standard load and extra load tires. The U.S. Tire Manufacturers Association has requested that NHTSA amend FMVSS No. 109 and 139 “to clarify marking and testing based on load classification,” and that it specifically clarify “whether 350 kPa is acceptable as a ‘Maximum Permissible Inflation Pressure’ marking for XL tires.”3 NHTSA is considering that request. However, as they currently stand, the testing requirements in Tables I-C and II of FMVSS 109 make no reference to load classification and are based solely on a tire’s maximum inflation pressure. 

I hope this information is helpful. If you have any further questions, please feel free to contact David Jasinski of my office at (202) 366-2992.

Sincerely,
ADAM RAVIV
Adam Raviv Chief Counsel

Dated: 8/8/24
Ref: Standard No. 109

2 FMVSS No. 109 has never referred to the terms “standard load,” “extra load,” or “reinforced” tires. 58 FR 59227 (Nov. 8, 1993).
3 See Docket No. NHTSA-2019-0011-0017.