| Report to Congress
Status Report on Establishing a Federal Motor Vehicle Safety Standard for Frontal Offset Crash Testing
TABLE OF CONTENTS
II. COMPARATIVE EVALUATION OF EU DIRECTIVE 96/79/EC AND CURRENT FRONTAL TEST RESULTS
III. TEST PLAN
IV. ADVANCED FRONTAL PROTECTION PROGRAM
List of Attachments
As part of the House of Representatives Conference Report 104-785, to accompany H.R. 3675, the National Highway Traffic Safety Administration (NHTSA or the agency) was directed to use $340,000 toward establishing a Federal motor vehicle safety standard for frontal offset crash testing. This report responds to these directions and provides a status of NHTSA's activities in developing a standard that reflects efforts to enhance international harmonization.
Federal Motor Vehicle Safety Standard (FMVSS) No. 208, Occupant Crash Protection, was promulgated by NHTSA in 1972 to reduce the number of fatalities and injuries occurring as a result of frontal crashes. The standard has been upgraded over the years to include requirements for automatic restraint systems and air bags. However, even after full implementation of driver and passenger air bags, as required by the National Highway Traffic Safety Administration Authorization Act of 1991, estimates are that frontal impact crashes involving cars and light trucks will still account for about 14,500 fatalities and about 130,000 moderate-to-critical injuries, including 50,000 injuries to lower limbs.
In this decade, the significance of this motor vehicle safety problem has been recognized by other countries. Recently, the European Union adopted EU Directive 96/79 EC for frontal crash protection, which will become effective in October of 1998 for new types and models of vehicles, and October of 2003 for all new vehicles. The Federal Office of Road Safety in Australia recently enacted Australian Design Rule No. 69 for new models of vehicles, which is similar to FMVSS Standard No. 208. The Japanese Ministry of Transport enacted Safety Regulation for Road Vehicles, Article 18 which is also similar to the FMVSS Standard No. 208. Both countries are currently assessing the benefits of adopting a supplemental regulation similar to the EU Directive 96/79 EC.
Although both the European and U.S. standards address the frontal crash safety problem, there are significant differences in the prescribed test procedures and injury response criteria between the FMVSS No. 208 and the EU Directive 96/79 EC. The most important of these is that the U.S. Standard 208 procedure requires successful crash testing of a vehicle into a perpendicular rigid barrier; while the EU 96/79 EC test is an offset collision, involving only part of the frontal structure of the vehicle, into a fixed deformable barrier. The FMVSS No. 208 Standard is most effective in preventing head, femur and chest injuries and fatalities. However, it does not directly address lower limb and neck injuries. Additional test dummy injury response criteria, particularly for the neck and lower limb, have been included in the EU Directive 96/79 EC. NHTSA is currently evaluating the EU 96/79 EC test procedure to determine if there are any additional safety benefits to be realized by adopting the EU 96/79 EC standard as a supplement to the U.S. Standard 208.
NHTSA has made a preliminary assessment that the adoption of the EU 96/79 EC frontal offset test procedure, in addition to the current requirements of FMVSS No. 208, could yield benefits in terms of a reduction in lower limb injuries. NHTSA has reviewed injury response data generated by the agency, other highway safety organizations, and auto manufacturers which support this assessment. NHTSA plans to use the $340,000 in funding provided by Congressional conferees to conduct crash tests in the remainder of this fiscal year in order to further evaluate the potential safety benefit of this approach. A test plan for this program is presented in this report. The benefits of extending the test requirements to address the effects of occupant size will also be studied. If a supplemental requirement is added to FMVSS No. 208, structural changes to the front end of passenger vehicles may make them more aggressive in side impact crashes. Thus, the possible adverse effects on vehicle fleet compatibility are being considered.
NHTSA does not plan to adopt the EU Directive 96/79 EC as a replacement for U.S. Standard 208, but is considering the option of harmonization to the standard as a supplemental regulation if the benefits to lower limb injuries are demonstrated and proven to be cost effective. Since 1989, NHTSA has had an advanced frontal crash protection research program underway to develop supplemental procedures, develop improved injury criteria, and evaluate the injuries associated with occupant size. This effort has led to the development of a frontal offset crash test procedure using a moving deformable barrier. Preliminary findings suggest that this procedure may have the potential for addressing additional fatalities and serious injuries that occur in higher severity frontal crashes. NHTSA will continue this research since harmonization to this approach over a longer time frame could yield significant reductions in fatalities and injuries.
Future crash testing plans may address the repeatability and reproducibility of the EU 96/79 EC test procedure, the performance of additional dummy sizes in frontal crashes, and the feasibility of the test procedure for lighter or heavier vehicles which will not be tested during this fiscal year. In addition, NHTSA will need to conduct the requisite benefit and cost analysis before deciding on whether to promulgate a supplemental standard to FMVSS No. 208.
In September of 1996, Congressional conferees provided an increase of $340,000 to the 1997 budget request for vehicle safety standards to the National Highway Traffic Safety Administration (NHTSA). The conferees stated that the funding "should be used toward establishing a federal motor vehicle safety standard for frontal offset crash testing." They directed NHTSA "to work with interested parties, including the automotive industry, to develop such a standard under established rulemaking procedures" and further stated that "these activities should reflect ongoing efforts to enhance international harmonization of safety standards." NHTSA was instructed to provide "a status report to the House and Senate Appropriations Committees on standards development and harmonization with current European and Australian offset crash tests during the fiscal year 1998 hearings." (1)
In response to this directive, NHTSA has undertaken a review of frontal crash protection test results and is continuing discussions toward harmonization of its frontal protection standards with those under development in Europe and Australia. During this fiscal year, NHTSA plans to conduct additional frontal offset testing. The purpose of this report is to present the results to date of NHTSA's review, describe frontal offset crash test plans, and provide additional results from its frontal crash protection research program which will have a bearing on future harmonization discussions.
NHTSA Frontal Protection Program
Occupant protection in frontal crashes has been a major focus of NHTSA automotive safety efforts for the past 25 years. In January of 1972, NHTSA began requiring that all passenger cars, multipurpose passenger vehicles, trucks and buses meet Federal Motor Vehicle Safety Standard (FMVSS) No. 208, Occupant Crash Protection.(2) The main dynamic performance requirement in this standard involves successful crash testing of a test vehicle into a rigid barrier with both restrained and unrestrained adult dummies at any speed up to and including 48 kilometers per hour (kph), or 30 miles per hour(mph), at all angles between perpendicular and 30 degrees to either side. Due to the air bag aggressivity issues, NHTSA has temporarily amended FMVSS No. 208 so that future passenger cars and light trucks can have the option of using a sled test for the unrestrained dummy.(3) This amendment was designed to enable auto manufacturers to "depower" air bags. Vehicle crashworthiness requirements are specified in terms of force and acceleration measured on an unrestrained anthropomorphic 50th percentile male dummy positioned in the test vehicle. Equipment requirements for active restraint systems are also specified in the standard. The test conditions specified in the FMVSS No. 208 standard also serve as the basis for the NHTSA's New Car Assessment Program (NCAP) consumer information program, with the exception that, in the NCAP test, speeds up to 56 kph, or 35 mph, are employed and the dummy is belt restrained. This program, which began in 1979, allows NHTSA to rate vehicle crashworthiness for many new make-model vehicles on an annual basis.
Within the next few years, essentially all passenger cars and light trucks in the U.S. fleet will have air bags. Even after full implementation of driver and passenger air bags as required by FMVSS No. 208, estimates are that frontal impact crashes will still account for about 14,500 fatalities and 130,000 moderate-to- critical injuries per year, including 50,000 injuries to the lower limbs.(4) Since 1989, NHTSA has had an ongoing research program to address these fatalities and injuries and provide a basis for the possible future upgrade of FMVSS No. 208. This effort includes developing supplementary test procedures, developing improved injury criteria including criteria for assessing injuries to additional body regions, and evaluating the injuries associated with occupant size.
Frontal Protection Developments in Europe, Australia and Japan
NHTSA has continued to engage its counterparts in the European community in discussions regarding frontal impact protection. As early as 1979, NHTSA researchers outlined the NHTSA's research findings and regulatory requirements at international meetings and conferences. However, with belt use rates at 95 percent, there was little incentive for Europeans to adopt the U.S. unrestrained test requirement or begin a research program, prior to 1990. However, in 1990, with the available crash data showing increased fatality and injury rates in frontal crashes, the Europeans began to consider the development of a frontal crash protection regulation in addition to regulations on restraints and anchorages.
The European Experimental Vehicles Committee (EEVC) created a Working Group (WG-11) for the Improvement of Protection in Frontal Collision and a Working Group (WG-12) for Frontal Dummy Development to produce a regulation. The EEVC invited representatives from NHTSA, the Japanese Ministry of Transport, Transport Canada, the Federal Office of Road Safety in Australia, and the automotive industry to participate in this effort. In the interest of international harmonization, NHTSA has worked closely with both of the EEVC working groups. NHTSA representatives have participated with the hope that the Europeans would improve existing component regulations when applicable, rather than develop a new regulation with different specifications and procedures.
After examining available crash data, the WG-11 concluded that the most effective way to reduce deaths and serious injuries in frontal impacts is to introduce a full scale impact test that simulates the dynamic conditions of frontal car-to-car impacts at 60 kph or greater. They concluded that many car-to-car impacts were offset, which involves only part of the frontal structure, instead of a full frontal collision. These impacts occur between two deformable objects, rather than the full overlap impact into a perpendicular rigid block as specified in FMVSS No. 208. Diagrams depicting the configuration of both tests are presented in Attachment A. The working group also noted that cars exhibited a larger degree of intrusion in offset impact tests, as compared to the FMVSS No. 208 tests. This was significant since it has been shown that the risk of injury usually increases with the degree of intrusion.(5) With respect to the test barrier, WG-11 found that a moving deformable barrier face, such as the one used in FMVSS No. 214 for Side Impact Protection, was a reasonable representation of real world impacts and that the principal effects were not too sensitive to the actual stiffness of the deformable elements.
However, for WG-11 to recommend such a barrier be adopted and to conduct tests at a speed of 60 kph or greater would have resulted in major design changes in vehicles. These changes would have resulted in higher costs for smaller European vehicles, such that their marketability would have been seriously compromised. Instead, the EEVC concentrated on developing an offset test into a fixed deformable barrier and made a recommendation to the member states for a two-stage approach. The first stage was to be based on a 30 degree angled rigid barrier test with an anti-slide device, referred to as ASD-30, and the second stage was to be based on an offset fixed deformable barrier. The impact speed was to be initially 56 kph, but would be raised to 60 kph once the manufacturers had become accustomed to meeting the requirements. The specifications for the anthropomorphic dummies and vehicle conditions were identical to those in the FMVSS No. 208 standard, except for the restraint option. Due to their high seat belt usage rates, the Europeans test solely with restrained dummies. Finally, the injury criteria were to include a lower limb response, a requirement not found in FMVSS No. 208. In December 1996, the European Union adopted EU Directive 96/79/EC for frontal crash protection, effective October 1998 for new types of vehicles, and October 2003 for all new vehicles.(6) A summary of this standard is also presented in Exhibit A of Section II. The first stage angled rigid barrier test with ASD-30 was omitted and the fixed deformable barrier is required in the Directive.
In Australia, the Federal Office of Road Safety requires vehicles to meet the Australian Design Rule (ADR) No. 69, which specifies head, chest and femur dummy criteria in a dynamic full frontal barrier crash test at 48 kph. This regulation is based on the U.S. FMVSS No. 208 regulation with provisions for restraining the test dummies. ADR No. 69 became effective July 1, 1995 on all new design models of passenger cars and January 1, 1996 on all new passenger car vehicles. In 1993, Australia began their NCAP with full barrier, frontal impact testing at 56 kph for consumer information in Australia.(7) Australia added the EU Directive 40 percent offset test at 64 kph to their NCAP in 1994 and is currently assessing the benefits of requiring such a standard as a supplement to ADR No. 69. The proposed implementation date is 1999.
In Japan, the Japanese Ministry of Transport recently enacted Safety Regulation for Road Vehicles, Article 18. This standard specifies a test procedure in which a passenger car traveling at 50 kph collides into a full concrete barrier. Impacts to the head and chest are measured for both the restrained driver and passenger. The Japanese National Organization for Automotive Safety and Victims Aid began publishing NCAP data from 56 kph full barrier tests in 1996.
Approach To Harmonization
Any new frontal protection standard that NHTSA will consider adopting at this point will not replace the current FMVSS No. 208 test procedure, but would serve as an added requirement. This would be similar to the approach under consideration by Australia. While the current full barrier test of FMVSS No. 208 does not produce the vehicle intrusion observed in many real world crashes, it does depict those impacts which produce the highest risk of serious to fatal injuries resulting from frontal crashes. The EU 96/79 EC frontal test procedure, on the other hand, while addressing a very common crash mode, does not address the highest risk of serious to fatal injuries occurring in frontal crashes. From NHTSA's viewpoint, EU test conditions are not desirable as a replacement for FMVSS No. 208.
However, NHTSA is interested in adopting supplementary test procedures that will address the fatalities and injuries, especially lower limb injuries, that are currently not addressed by FMVSS No. 208. If this is to be accomplished, it must enhance the overall safety benefits. Hence, NHTSA is reviewing the EU Directive 96/79 EC from this standpoint. NHTSA is coordinating this effort with industry through the Motor Vehicle Safety Research Advisory Committee (MVSRAC) and with the Insurance Institute for Highway Safety (IIHS). Both groups have evaluated the EU directive on U.S. vehicles and have concluded that while the EU standard does not provide the same safety benefits as FMVSS No. 208, it may address some of the lower limb injuries that are currently not addressed by FMVSS No. 208.
A discussion of these data and all other available crash test and real world crash data and analysis reviewed by NHTSA is presented in Section II of the report. NHTSA also plans to obtain additional test data to reinforce its findings from the review and data analysis. The test plan for this effort is described in Section III. NHTSA has been developing an advanced frontal offset impact test procedure for the past several years. The procedure that is being developed differs considerably from the EU Directive 96/79 EC. This test involves the use of a moving deformable barrier at a speed of 60 kph or higher. The preliminary results of this program will be discussed in Section IV. Some additional comments on the need for future work before any decision on harmonization is made are provided in Section V.
Informal preliminary meetings with EU regulatory officials are planned in May 1997 to discuss these activities. As tests and analyses are completed, additional meetings with the EU will be held to ascertain the extent to which the adoption of an offset test requirement as a supplement to FMVSS No. 208 may be responsive to international harmonization.
II. COMPARATIVE EVALUATION OF EU DIRECTIVE 96/79 EC AND CURRENT FRONTAL TEST RESULTS
The test conditions and injury criteria prescribed in the EU Directive 96/79 EC and FMVSS No. 208 differ considerably. As stated earlier, FMVSS No. 208 involves successful crash testing of a test vehicle into a rigid barrier with adult dummies at any speed up to and including 48 kph, or 30 mph, at all angles between perpendicular and 30 degrees to either side. In the EU Directive 96/79 EC, test vehicles are crashed into a deformable barrier at a higher impact speed of 56 kph, at 40% overlap of the vehicle width directly in line with the barrier face. While the same Hybrid III test dummy is used, the EU Directive requires that the dummy be belt restrained. In some cases, the injury criteria used are the same. However, the EU Directive includes a measure of the neck, tibia, knee and viscous criteria response. These differences are summarized in Exhibit A.
Exhibit A. General Summary of the Test Requirements for the FMVSS No. 208 and EU Directive 96/79 EC.
|FMVSS No. 208||EU Directive 96/79 EC|
|Impact Speed(a)||48 kph or 30 mph||56 kph or 35 mph|
|Impact Object||fixed rigid barrier||fixed deformable barrier|
|Vehicle Frontal Overlap With Barrier||full frontal||40% overlap of the vehicle width directly in line with the barrier face (see attachment A)|
|Dummy Type and Conditions(b)||unrestrained and belt restrained, 50th percentile Hybrid III male||belt restrained, 50th percentile Hybrid III male|
|Injury Criteria(c)||includes threshold criteria for the head, chest deceleration, chest deflection, and femur (proximal) lower leg||includes the same threshold criteria, and in addition, viscous criteria (V*C), the neck, the knee, lower leg bending (tibia index), foot/ankle compression and compartmental intrusion.|
(a) NCAP test is conducted at 56 kph or 35 mph.
(b) the 50th percentile, or mid-sized, male test dummy represents the mean of an adult male as specified for the total age group.
(c) criteria for the head are 1,000 HIC, chest deceleration is 60 g, chest deflection is 76 mm, and femur is 10,000 newtons.
Review of Available Data
During the past two years, frontal crash tests have been conducted by the governments of Canada, Australia, Japan, the Insurance Institute for Highway Safety, automobile manufacturers, and NHTSA to evaluate the crashworthiness benefits of the EU 96/79 EC standard. The NHTSA has been sharing available test results with other organizations and attempting to coordinate its efforts. In the following paragraphs, the test results and the issues that have been raised are discussed.
The Canadian Government recently conducted a test program to validate the 40 percent offset crash procedure specified in the EU Directive 96/79 EC.(8) Four separate left-hand drive passenger vehicles were crashed at the speed of 56 kph and at a higher speed of 60 kph. All four vehicles were 1994 or 1995 make models -- a Ford Aspire, a GM Saturn, a Hyundai Excel, and a Dodge Neon. In the NCAP program, NHTSA crashed similar vehicles into a rigid barrier at 56 kph with all dummies fully restrained. In comparison to the NCAP test results, the EU 96/79 EC offset test procedure followed by the Canadian team resulted in lower force loadings (i.e., injury measures) to the head and chest of the driver dummies in all of the tests, except for the '94 Hyundai Excel. These results are summarized in Attachment B.
The lower legs of the dummies were fully instrumented in the Canadian offset crash tests. By contrast, the lower legs of the dummies in NHTSA's NCAP tests were not equipped with instrumentation since this requirement is not specified in FMVSS No. 208. In the Canadian offset tests, the lower leg readings exceeded the allowed tibia criteria values of the EU Directive on three occasions out of eight, at the impact speed of 60 kph. These results are summarized in Exhibit B.
At 56 kph, the left leg of the driver dummy in the Dodge Neon exceeded the tibia criteria. At 60 kph, the left and right legs of the driver dummy in the Dodge Neon exceeded the criteria, while the left leg of the driver dummy in the GM Saturn exceeded the threshold. Although there are no tibia data for these specific cars from NCAP tests at 56 kph, NCAP data from other vehicles with fully instrumented lower legs suggest that the dummies would generally have readings below the tibia injury criteria.
Exhibit B. Results for Lower Legs of the Hybrid III 50th Percentile Dummy by Vehicle Type and Impact Speed
( - indicates when the dummy measures exceeded the allowable tibia injury criteria).
|Test Vehicle||40% Offset @ 56 kph||40% Offset @ 60 kph|
|Left Leg||Right Leg||Left Leg||Right Leg|
Insurance Institute for Highway Safety
The Insurance Institute for Highway Safety (IIHS) in 1994 began testing cars under the EU Directive 40 percent offset test condition at 64 kph.(9) The IIHS contends that full-width and offset barrier crash tests complement each other. In the full frontal test, the safety of the combination of the structure, belt, and air bag should be evaluated. But the situation is different for the offset crash test. Only one side of the structure carries most of the loading. The IIHS concluded that full width tests are especially demanding of restraints, but not so much of structures for vehicles in the US fleet; while the reverse is true in offset tests. NHTSA has compared the results of full-frontal barrier NCAP tests at 56 kph with the IIHS 40 percent offset test at 64 kph.(10) Based on a study of comparative crash test results for 21 vehicles, the NHTSA concluded that the full frontal crash test is a more stringent evaluation of the restraint system performance. On the other hand, due to more intrusion, the probability of lower leg injury will be better determined in the EU offset crash procedure.
Volvo has compared three frontal crash test methodologies -- the EU Directive offset test at 56 kph, roughly the EU Directive offset test at 65 kph, and a full frontal barrier NCAP type crash test at 56 kph.(11) Volvo used a Hybrid III dummy placed in the driver seat of a Volvo 850 for all test configurations. They concluded that the full frontal barrier crash at 56 kph fully taxes the capacity of the safety system (i.e., vehicle structure, belt, and air bag) for the head and chest. As in the Canadian study, dummy readings at 56 kph with the EU offset procedure exceeded few if any of the injury criteria, with two exceptions. The driver tibia index exceeded the 1.3 requirement in the Dodge Neon test vehicle, and the driver head acceleration was 83.99 g in the Hyundai Excel. At the higher speed of 65 kph, they found the EU Directive test procedure loads the lower leg with a higher bending moment and higher compressive loads.
Summary of Results
Based on the results of the studies to date, the EU Directive 96/79/EC test appears to be a more benign test, in terms of head and chest injury measures, than fixed barrier or vehicle-to-vehicle impacts at the same velocity or even the current lower speed of 48 kph used in the FMVSS No. 208 barrier test. However, the EU Directive 96 offset test procedure does result in more compartment intrusion than tests with full frontal structure engagement and appears to result in lower leg (i.e., tibia) injury measures that are higher than those observed in the NCAP or FMVSS No. 208 procedure.
The EU 96/79 EC offset test provides for a lower level of head and chest protection for the occupants of vehicles than FMVSS No. 208. Its adoption may lead, however, to advancements in vehicle designs for the reduction of lower leg injuries. The European test procedure, by necessity, may not be considered an upgrade to the U.S. frontal requirement for fatality reduction. However, if the test results can be confirmed, it may provide significant additional lower leg protection. It should also be noted that harmonization with Europe should only involve vehicles which are sold worldwide, or at least in the U.S. and Europe, while the EU 96/79 EC test condition must apply to many cars which are sold only in Europe.
Another benefit in developing a new test procedure is the opportunity to propose state-of-art injury measures and associated instrumentation for the test surrogate beyond what is in current standards. The current FMVSS No. 208 specifies criteria for head injury in the form of a HIC of 1000, chest in the form of deceleration G's of 60 and chest deflection of 76 mm, and femur loads of 10,000 newtons. New injury measures which could be included in a EU 96/79/EC Directive type test procedure may include the following (with values given being the maximum allowable): a peak resultant head acceleration of 80 g; neck forces and moments with criteria to be determined; a chest - viscous criteria (V*C, rate of deflection times deflection) of less than 1 m/s; and, for the tibia, a current proposed criteria is axial compression of 8 kN, tibia index of 1.3, and knee displacement of 15 mm.
In addition, steering wheel displacement at the center of the hub should not exceed 100 mm in the rearward horizontal direction and 80 mm vertically. Upward rotation of the steering column and wheel is to be less than 25 degrees. The dummies must be capable of being removed intact without adjusting the seating position after the test and must be able to be used in further testing.
The EU 96/79 EC test procedure requires the use of 50th percentile adult male Hybrid III dummies. On August 23, 1996, the American Automotive Manufacturers Association (AAMA) petitioned NHTSA to change FMVSS No. 208 test procedures to allow reduced air bag inflator output.(12) One of the issues addressed is the injuries and fatalities involving the interaction of the air bag with small occupants seated in the front seat. NHTSA wants to reduce injuries and fatalities for all occupants. NHTSA is planning to use both 50th percentile adult male and 5th percentile adult female Hybrid III dummies in future offset testing. This will help evaluate the effects of crashes to different size occupants. In the future, NHTSA is planning to gain additional information on the interaction of the 95th percentile adult male dummy with depowered air bag systems.
In the EU Directive 96/79 EC test procedure, a finite amount of the crash energy is absorbed by the fixed deformable barrier. The amount of energy is a larger proportion of the total crash energy for a small (light) car than a large (heavy) car. Therefore, to achieve a level of performance comparable to a small car, the front structure of a large car may need to be designed to crush more or to crush at a higher force level to absorb the additional energy. If the design of a small car was governed by the test, it is possible that the structure of the small car could become softer. If the large car is designed with a higher force level and the small car is designed softer with a lower force level, this could lead to less compatibility in crashes between large and small cars. NHTSA notes, however, that there is no intention to replace the present full barrier test with the EU offset test, but only to possibly adopt the EU test as a supplement. Therefore, manufacturers would probably base the design of their structure on optimum performance of not only this offset test but the existing FMVSS No. 208 and NCAP tests. The IIHS higher speed offset tests which have received extensive media coverage and consumer interest along with NCAP may already be resulting in better designs.
III. TEST PLAN
As mentioned earlier, full frontal crash tests have been performed under FMVSS No. 208 at 48 kph with unrestrained occupants and under NCAP at 56 kph with restrained occupants. The EU 96/79 EC offset frontal barrier crash tests have been performed by Transport Canada at 56 kph and 60 kph and by the Insurance Institute for Highway Safety at 64 kph. All of these frontal crashes were conducted using the 50th percentile male Hybrid III dummy. NHTSA proposes to use these tests as the starting point to further quantify relationships between the full barrier frontal crash and the EU Directive 40 percent offset crash.
The size of the occupant may be important in determining the safety value of different frontal crash procedures. Previous research into frontal crash protection has suggested that trauma risk level differs by occupant size.(13) In the U.S., recent experience with air bags has suggested that the smaller occupant may be more at risk because they are in closer proximity than larger occupants, to the deploying air bag when driving a vehicle. Also, Transport Canada tests have shown potentially serious-to-fatal neck loadings for the driver with the seat forward in full, rigid-barrier tests with belted, 5th percentile female dummies. NHTSA has received two petitions to incorporate the 5th percentile female Hybrid III dummy into FMVSS No. 208. (14),(15)
NHTSA will use the available $340,000 funding to conduct eight crash tests. Within the next six months, tests will be conducted with three passenger cars -- Dodge Neon, Toyota Camry, and Ford Taurus -- using two dummies, the 50th percentile male Hybrid III and the 5th percentile female Hybrid III dummy. The test matrix is presented in Exhibit C. Vehicle selection was based on choosing vehicles for which i) frontal impact test data already exists, ii) there are a large number of these cars sold in the U.S., and iii) there is a sales presence of these cars throughout the world. Of the three vehicles chosen, the Dodge Neon was one of the passenger cars tested by Transport Canada. The Ford Taurus and the Toyota Camry are two passenger cars that have been tested extensively by NHTSA and the Insurance Institute for
Highway Safety. NHTSA envisions conducting additional frontal offset tests with the 95th percentile male Hybrid III dummy as the new depowered air bags are sold in passenger cars in the U.S.
Exhibit C. Test Matrix
( = data already exists for this test condition and make model combination).
|Frontal Test||Dodge Neon||Toyota Camry||Ford Taurus|
|Full @ 48 kph with 50th% male dummy, unrestrained(a)|
|Full @ 56 kph with 50th% male dummy, restrained(b)|
|Full @ 48 kph with 5th% female dummy, restrained|
|40% Offset @ 60 kph with 50th% male dummy, restrained(c)|
|40% offset @ 64 kph with 50th% male dummy, restrained(d)|
|40% offset @ 60 kmph with 5th% female dummy, restrained|
(a) NHTSA FMVSS No. 208 crash test results
(b) NHTSA NCAP crash test results
(c) Transport Canada EU 96/79 EC test results
(d) IIHS EU 96/79 EC test results
(Note: the 40% offset tests will be conducted at 60 kph. Presently, EU directive 96/79 EC specifies 56 kph with a potential increase to 60 kph in the future. Discussions with the MVSRAC working group, including representatives from the auto industry, indicate that, given the results to date from the Transport Canada tests and the high likelihood that EU will increase the test speed, 60 kph is the more appropriate test speed.)
After the testing is complete, data will be available for all combinations of test conditions and vehicles presented in the matrix. With these data, NHTSA will then be able to compare the injury response of the Hybrid III dummies in the full frontal and the 40 percent offset crash tests. The analysis will focus on answering three questions.
Question 1. Does the data using the 50th percentile male Hybrid III dummy support the previous findings that the full frontal test appears to load the head and chest of the dummies (more than the lower extremities), while the EU Directive offset test appears to load the lower extremities of the dummies (more than the head and chest)?
Question 2. Does the 5th percentile female Hybrid III dummy, because of its different anthropometric properties, demonstrate significant injury risks to smaller occupants that are not indicated by the larger 50th percentile male Hybrid III dummy?
Question 3. Does the 5th percentile female Hybrid III also suggest the previous findings using the 50th percentile male Hybrid III dummy? In other words, does the 5th percentile female dummy in the full frontal test appear to indicate a greater injury potential to the head and chest than to the lower extremities, while in the EU Directive offset test, does this smaller dummy appear to indicate a greater injury potential to the lower extremities than to the head and chest?
Test Dummies and Instrumentation
The offset frontal testing will utilize instrumentation currently available for the Hybrid III dummies to allow complete comparison between the full and offset barrier tests. This includes a fully instrumented head, a six-axis upper neck load cell, a sternal deflection gage, spine and pelvic accelerometers, and a femur load cell. Since offset crashes tend to result in a high incidence of lower extremity injuries, fully instrumented dummy legs will be used. Lower leg instrumentation includes two tibial load cells, a knee slider, and tibial plateau load cells. This instrumentation will allow measurement of forces and moments acting on the knee and tibia. These dummy legs are currently available for the mid-sized, or 50th percentile, male and the small, or 5th percentile, female. Fully instrumented dummy legs should be available in the near future for the large, or 95th percentile, male. Data collected from these transducers will allow calculation of currently recommended injury criteria for direct comparison to the EU requirements. Additional instrumentation, as appropriate, will be used to provide data for the evaluation of other injury criteria.
As illustrated in Exhibit A, injury criteria specified in the EU 96/79 EC offset test protocol include HIC, individual neck loads, sternal chest deflection, viscous criteria (V*C), femur load, tibial compression, and the tibia index. Current offset frontal testing should utilize the injury criteria specified in the FMVSS No. 208 standard, as well as additional criteria based on the EU 96/79 EC test protocol. Details of the criteria that include both the requirements of FMVSS No. 208 and EU 96/79 EC are listed below.
Head -- Head Injury Criterion (HIC) should not exceed 1000 and the resultant acceleration shall not exceed 80g for more than 3 milliseconds (ms); a rotational head injury criterion is currently under evaluation at NHTSA and may also be assessed in this program.
Neck -- The neck injury criterion as contained in the recent amendment to FMVSS No. 208 will be used. Flexion bending moment should not exceed 190 Newton meters (Nm), extension bending moment should not exceed 57 Nm, axial tension should not exceed a peak of 3300 Newtons (N), fore and aft shear should not exceed a peak of 3100 N. The axial tension and shear should meet the time dependent functions as specified in the EU directive. In addition, the Nij, a recently formulated index which combines the individual injury parameters into a single normalized value, will be assessed.
Chest -- Chest acceleration should not exceed 60 g's. Viscous Criteria (V*C) should be less than 1.0 m/sec. Chest deflection should be less than 50 mm. A dichotomous model developed by NHTSA, combining chest accelerations and deformations, will be also evaluated.
Lower Extremity -- Time dependent femur loads should not exceed a peak of 9.07 kN. Axial compression of the tibia should not exceed 8 kN. The tibia index (TI) measured at the top and bottom of each tibia should not exceed 1.3. Displacement of knee slider should not exceed 15 mm.
NHTSA has a 50th percentile male Hybrid III dummy available for these tests. Following the acquisition of a 5th percentile female Hybrid III dummy and deformable barrier material this spring, testing will be conducted in three phases.
Phase I: The Camry and Taurus vehicles will be tested in the EU offset condition at 60 kph impact speed. A 50th percentile male Hybrid III dummy will be used.
Phase II: The Neon, Camry, and Taurus vehicles will be tested in full frontal condition at 48 kph impact speed. A 5th percentile female Hybrid III dummy will be used.
Phase III: The Neon, Camry, and Taurus vehicles will be tested in the EU offset condition at 60 kph impact speed. A 5th percentile female Hybrid III dummy will be used.
It is anticipated that this testing program will be completed by the end of this fiscal year which is September 30, 1997. The allocation of the funding provided for fiscal year (FY) 1997 and the proposed budget for FY 1998 testing is presented in
The funding for FY 1998 will be used to procure the large, or 95th percentile, male hybrid III dummies and instrumentation and to conduct the following six tests.
Full frontal condition at 48 kph impact speed with the Neon, Camry, and Taurus
EU offset condition at 60 kph impact speed with the Neon, Camry, and Taurus.
The 95th percentile male hybrid III dummies will be restrained in the driver and right passenger seating locations of each of these tests. Data from these tests will complete an initial set of information for all adult size dummies in both the FMVSS No. 208 test condition and the EU offset test condition. Additional activities that may be required are discussed in Section V.
Exhibit D. Budget for 1997 and 1998 Frontal Offset Testing.
|Vehicle Purchase||$ 140,000||$ 100,000|
|Vehicle Testing||$ 160,000||$ 115,000|
|Dummy Purchase/ Calibration/Refurbishing||$ 15,000||$ 100,000|
|Quality Assurance of Testing Data||$ 20,000||$ 20,000|
|Administrative Costs||$ 5,000||$ 5,000|
|TOTAL||$ 340,000||$ 340,000|
IV. ADVANCED FRONTAL PROTECTION PROGRAM
It appears that adoption of the EU Directive 96/79 EC test procedure may provide some benefit in reducing lower leg injuries in frontal crashes. The test data which NHTSA plans to obtain in FY 1997 and FY 1998 may reinforce this observation. However, even if additional benefits can be obtained by adopting a supplementary procedure consistent with the European 96/79/EC Directive, NHTSA must still consider the benefits of new test procedures aimed at reducing overall fatalities and injuries resulting from frontal crashes. As mentioned, NHTSA has undertaken a research program during the past few years, with the goal of developing a moving barrier offset test and improved criteria for assessing injuries to all regions of the body. To better replicate what actually occurs in a frontal crash and set testing priorities, a substantial effort has been underway to evaluate reported crash data on the basis of injury risk and examine various crash test conditions such as car-to-car, moving barrier-to-car, and car-to-stationary barrier. NHTSA is also constantly evaluating new barrier materials and has an ongoing effort to improve the biofidelity of test dummies.
The preliminary results of this research have led to the development of a test procedure which simulates a moving car-to-car left oblique, left frontal offset crash. Most researchers, including those in the European community, recognize that a moving deformable barrier (MDB) could provide a more reasonable representation of real world impacts. This test procedure has been developed based on the knowledge that, in the next few years, a significant portion of the U.S. passenger vehicle fleet will consist of multipurpose vehicles such as vans and sport utility vehicles. NHTSA believes that the results of this ongoing program could have a significant bearing on future harmonization discussions and, for that reason, a comparison of the preliminary results from this testing program with the EU 96/79 EC procedure is provided in the following paragraphs.
The test developed by NHTSA is a moving deformable barrier (MDB) crash which simulates two cars in a frontal collision at 56 kph each. This test was based on an analysis of real world crash data and the results of a number of tests described in Attachment C. This collision is similar in severity to the NCAP test at 35 mph, but since the crash is offset and oblique, the crush to the subject vehicle is more extensive. Early in the development of this procedure, tests were planned on vehicles using the proposed EU Directive 96/79/EC fixed barrier. After one test, NHTSA concluded that the EU procedure would not seriously challenge the structure and crash performance of most vehicles sold in the U.S. market relative to the FMVSS No. 208 requirements. Similarly, none of the passenger cars in the EU tests conducted by Transport Canada exceeded the requirements of FMVSS No. 208. However, as noted, the potential for lower limb injuries does increase in the EU test condition.
Vehicle crash responses (crash pulses) measured in the occupant compartment from the average EU 96/79 EC type tests conducted by IIHS have been compared to the average car-to-car offset tests and the average offset oblique tests with the moving deformable barrier (see Attachment D). In the IIHS tests, there is a difference in loading of the vehicle structure from real world crashes. The deformable barrier test produces vehicle crash pulses in the subject car nearly identical to the crash pulses obtained by car-to-car testing.
Further comparisons have been made on the basis of theoretical energy absorbed by subject cars when exposed to various tests, as discussed above in Section II under Compatibility Concerns.
In the moving deformable barrier testing, the smaller vehicle is subjected to a harsher crash environment due to higher energy absorption and a higher velocity change, which is representative of the overall crash environment. The natural tendency on the part of vehicle design engineers to meet the test requirements may be to increase the stiffness of small cars, as well as improving restraints, to neutralize the increased crush requirement. On the other hand, large cars generally would be subjected to a less severe crash environment in terms of velocity change, but a large stiff car would see a harsher crash environment in terms of crash pulse in this procedure. Therefore, large car stiffness would likely be reduced or at least maintained at a minimum level in meeting the requirements of this procedure. Fleet compatibility, thus, could improve in response to the moving deformable barrier test procedure in order to optimize the vehicle structure to provide an acceptable or high level of occupant protection.
V. FUTURE EFFORTS
The immediate concern of NHTSA's analysis is to establish whether the EU Directive 96/79 EC test procedure (or a slight variant, using the 5th percentile female dummy and/or the 95th percentile male dummy) will provide any benefit for injury reduction, primarily for lower leg trauma. Future testing plans will be made once the test results are known. If it is determined that there are sufficient benefits from adopting the EU Directive 96/79 EC (or the 5th/95th percentile variant) as a supplementary test procedure, then there are several issues that need to be resolved prior to any decision. At this time, it is envisioned that future crash testing plans will address: the repeatability and reproducibility of the EU Directive test procedure; the performance of the 5th percentile female and 95th percentile male dummies in frontal crashes; and the feasibility of the EU Directive test procedure for lighter or heavier cars than those tested in FY 1997 and planned for testing in FY 1998. NHTSA has had frequent discussions with the insurance industry and automobile manufacturers and is actively participating in the Motor Vehicle Safety Research Advisory committee meetings where some of these issues are raised.
A reduction in lower leg injuries would benefit occupant protection. A number of studies have reported that lower leg injuries occur more frequently in frontal crashes. These injuries, while not necessarily life threatening, are often disabling and extremely painful. Occupants who suffer from these types of injuries require considerable rehabilitation, which is very costly to society in general. This is clearly a significant motor vehicle safety problem, NHTSA will need to conduct the benefit/cost analysis for any notice of proposed rulemaking on frontal offset crash testing. However, some preliminary data are available. In the 1993-1994 period, NHTSA estimates that lower extremity injuries cost society approximately $4.4 billion -- approximately 5.6 percent of the total costs resulting from all motor vehicle injuries -- based on a statistical sample of police reported crashes. More significantly, nearly 570,000 life-years were lost to lower extremity injuries. In terms of the crash survivor's capacity to function, this figure represents 40 percent of the total reduction in functional capacity by survivors of all types of motor vehicle crashes.(16) These and other issues, such as the costs of compliance with this test requirement, will need to be studied further before any decision on harmonization can be made.
LIST OF ATTACHMENTS
Attachment A. Configurations for the FMVSS 208 and EU 96/79 EC Frontal Offset Test Procedure.
Attachment B. Comparison of Driver Head and Chest Injury Criteria in the Transport Canada 40 Percent Frontal Offset and NCAP Tests.
Attachment C. Summary of Results from NHTSA Advanced Frontal Crash Program.
Attachment D. Car-to-Car Pulse vs. IIHS (or EEVC) Pulse.
Attachment A. Configuration for the FMVSS 208 and EU 96/79
Frontal Offset Test Procedure
Attachment B. Comparison of Driver Head and Chest Injury Criteria in the Transport Canada 40 Percent Frontal Offset and NCAP Tests.
|Test Vehicle||EU 96 Offset @ 56kph||EU 96 Offset @ 60kph||NCAP Full Frontal @ 56kph||EU 96 Offset @ 56kph||EU 96 Offset @ 60kph||NCAP Full Frontal @ 56kph|
|'94 Ford Aspire||265||302||487||34||38||53|
|'94 GM Saturn||288||368||705||27||36||51|
|'95 Dodge Neon||316||583||610||33||38||54|
|'94 Hyundai Excel||544||487||520||39||37||52|
Attachment C. Summary of Results from NHTSA Advanced Frontal Crash Program
Selection of Test Conditions by Crash Configurations
The analysis focused on defining an offset test procedure to supplement the FMVSS No. 208 test. Drivers of vehicles in the 1988-1995 National Analysis Sampling System (NASS) were grouped by damage descriptors into a frontal impact population. The frontal impact population is then separated into specific crash modes to identify impact configurations with high frequency and risk of injury to be simulated by crash test procedures. It should be noted that about 75 percent of frontal crashes are vehicle-to-vehicle, thus, the eventual test should probably simulate this mode.
The various frontal crash modes are grouped under a test condition which best simulates the crash. The following table shows the selected test conditions along with proportions of crash involved drivers fitting that condition and accompanying injury risks.
|Test Condition||% of Frontals||Serious Injury Risk||Moderate Risk|
Full barrier type impacts are less frequent but have a higher serious to fatal injury rate and than the other configurations. The relationship of overlap (in increments of less than 1/3, 1/3 to less than 2/3, and 2/3 and greater) to injury shows that the left oblique impact at over 2/3 overlap produces the highest injury rate of all offset impact modes. The left offset/oblique impacts with substantial overlap produce the highest rate of injuries of the offset impact test modes.
Four tests were conducted with an overlap of 70 to 80 percent at an oblique impact angle of 30 degrees. Test speeds were 121 to 127 kph closing velocity. Restrained Hybrid III 50th percentile male dummies were used. The subject car exceeded FMVSS No. 208 injury criteria in only the oblique tests; however, tibia moments were considered injurious in all tests. More overlap caused higher dummy measures for in-line but not for oblique tests. It was concluded that the oblique, offset test is the most severe configuration for occupant survival. The test uses a moving-deformable-barrier (MDB); this is the same barrier that is used for FMVSS No. 214, Side Impact Protection. The MDB is a honeycomb deformable element mounted on the front of a moving barrier. The selected condition for further evaluation was a vehicle-to-vehicle test, at a 30 degree angle and 50 to 60 percent overlap at 56 kph for each vehicle. The test configuration is illustrated below.
An additional test using the selected vehicle was conducted according to the EU Directive 96 test protocol, but with a speed of 65 kph. These results indicate that the test is very benign for both the dummy and the structure. Comparisons of some of the offset tests conducted by NHTSA, NCAP tests and the EU Directive 96 type tests are shown in the table on the next page.
As shown in the table, the head and chest measures in the EU Directive 96 test are lower than any of the offset tests and the NCAP test (femur loads are similar for all tests.) Also, tibia loads are lower in the EU Directive 96 test, especially when compared to the proposed offset/oblique tests.
|Test Condition||HIC <1000||Chest G's||Femur (Newtons)||Tibia (N-M)|
|Car-to-Corsica, Collinear, 50% overlap, 118 kph closing||781||41.9||6205||482|
|Car-to-Corsica, Collinear, 70% overlap, 118 kph closing||852||57.2||6868||392|
|Car-to-Corsica, 30 degree, 57% overlap, 121 kph closing||888||76.4||10231||374|
|Car-to-Corsica, 30 degree, 80% overlap, 127 kph closing||908||44.5||10466||395|
|Car-to-Taurus, Collinear, 50 % overlap, 112 kph closing||530||45.4||5654||184|
|Car-to-Taurus, 30 degree, 59 % overlap, 124 kph closing||411||51||5824||242|
|MDB-to-Taurus, 30 degree, 53 % overlap, 114 kph closing||461||54.8||6708||493|
|MDB-to-Taurus, 30 degree, 68% overlap, 113 kmph||620||61.8||15620||507|
|MDB-to-Taurus, 45 degree, 65% overlap, 109 kph||363||44.9||7223||338|
|Taurus-to-EEVC Fix Deform. Barrier, 50 % overlap, 64.2 kph||178||38.5||6154||142|
Attachment D. Car-to-Car Pulse vs. IIHS (or EEVC) Pulse.
1. House Conference Report No. 104-785 to accompany HR 3675, H10409, September 16, 1996.
2. Code of Federal Regulations, Title 49, Part 571.208, U.S. Government Printing Office, October 1, 1996
3. 62 Federal Register (March 19, 1997) 12960
4. Final Regulatory Evaluation, Action to Reduce the Adverse Effects of Air Bags, FMVSS No. 208, Depowering, 1997
5. Zuby, D.S. et al., "Intrusion and Lower Extremity Injury Risk in Offset Frontal Test Crashes", SAE Paper #950500, Society of Automotive Engineers, 1995.
6. Directive 96/79 EC of the European Parliament and of the Council on the Protection of Occupants of Motor Vehicles in the Event of a Frontal Impact, May 28, 1996.
7. McIntosh, L., " Consumer Needs in Vehicle Crash Rating Systems," The Fifteenth International Technical Conference on Enhanced Safety of Vehicles, Melbourne, Australia, May 13, 1996.
8. Welbourne, E.R., "Offset Frontal Crash Tests: Summary Results of a Programme to Validate the Proposed Test Protocol of EEVC Working Group 11," Technical Memorandum, Vehicle Systems Division, Transport Canada Road Safety, September 1996.
9. Insurance Institute for Highway Safety, "Crashworthiness," Brochure on frontal offset crash test performance, Insurance Institute for Highway Safety, North Glebe Road, Arlington, VA, November 1995.
10. Hackney, J. R., Kahane, C. J., and Chan, R., "Activities of the New Car Assessment Program in the United States," The Fifteenth International Technical Conference on Enhanced Safety of Vehicles, Melbourne, Australia, May 13, 1996.
11. Planath-Skogsmo, I., and Nilsson, R., "Frontal Crash Tests - A comparison of Methods," 38th Stapp Car Crash Conference Proceedings," Society of Automotive Engineers, Inc., November 1994.
12. American Automotive Manufacturers Association, "Petition for Rulemaking, FMVSS No. 208," submitted to the National Highway Traffic Safety Administration, August 23, 1996.
13. Stucki, S.L., Ragland, C., Hennessey, B., and Hollowell, W.T., "NHTSA's Improved Frontal Protection Research Program," Society of Automotive Engineers, Paper No. 950497, 1995.
14. Lindsey, A. G., "Petition Seeking to Change the Size of the Dummy in FMVSS No. 208," submitted to NHTSA on September 1, 1996.
15. American Automotive Manufacturers Association, "Petition for Rulemaking, FMVSS 208, " submitted to National Highway Traffic Safety Administration, August 23, 1996
16. Luchter, Stephen 1995. Long Term Consequences of Lower Extremity Injuries. International Conference on Pelvic and Lower Extremity Injuries Proceedings December 4-6, 1995