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In 2004, a model of a 6s6m ABS controller was developed in order to support NHTSA's efforts in the study of heavy truck braking performance. This model was developed using Simulink and interfaced with TruckSim, a vehicle dynamics software package, in order to create an accurate braking simulation of a 6×4 Peterbilt straight truck. For this study, the vehicle model braking dynamics were improved and the ABS controller model was refined. Also, the controller was made adaptable to ABS configurations other than 6s6m, such as 4s4m and 4s3m. Controller models were finally validated to experimental data from the Peterbilt truck, gathered at NHTSA's Vehicle Research and Test Center (VRTC).

In crashes between heavy trucks and light vehicles, most of the fatalities are the occupants of the light vehicle. A reduction in heavy truck stopping distance should lead to a reduction in the number of crashes, the severity of crashes, and consequently the numbers of fatalities and injuries. This study made use of the National Advanced Driving Simulator (NADS). NADS is a full immersion driving simulator used to study driver behavior as well as driver-vehicle reactions and responses. The vehicle dynamics model of the existing heavy truck on NADS had been modified with the creation of two additional brake models. The first was a modified S-cam (larger drums and shoes) and the second was an air-actuated disc brake system. A sample of 108 CDL-licensed drivers was split evenly among the simulations using each of the three braking systems. The drivers were presented with four different emergency stopping situations.

This paper describes ongoing research conducted by the National Highway Traffic Safety Administration (NHTSA) to evaluate the potential of safety restraints on large school buses. School bus transportation is one of the safest forms of transportation in the United States. Large school buses provide protection because of their visibility, size, and weight, as compared to other types of motor vehicles. Additionally, they are required to meet minimum Federal Motor Vehicle Safety Standards (FMVSS) mandating compartmentalized seating, emergency exits, roof crush and fuel system integrity, and minimum bus body joint strength.

Several thoracic and head protection side impact air bag systems (SAB) are emerging in the U.S. market and are projected to become prevalent in the fleet. These systems appear to offer superior protection in side crashes. However, concerns have been raised as to their potential for causing injury to out-of-position (OOP) occupants. This paper describes the National Highway Traffic Safety Administration (NHTSA) program for evaluation of the SAB systems for OOP occupants and provides a status report on the current research. The industry's Side Airbag Out-of- Position Injury Technical Working Group (TWG) recommended procedures for 3-year-old and 6-year-old occupants are evaluated. Additional test procedures are described to augment the TWG procedures for these occupants and 12-month- old infants.

Phase IV of the National Highway Traffic Safety Administration's (NHTSA) rollover research program was performed during the spring through fall of 2001. The objective of this phase was to obtain the data needed to select a limited set of maneuvers capable of assessing light vehicle rollover resistance. Five Characterization maneuvers and eight Rollover Resistance maneuvers were evaluated [1]. This paper is “Volume 2” of a two-paper account of the research used to develop dynamic maneuver tests for rollover resistance ratings. Test procedures and results from four Rollover Resistance maneuvers are presented. The Consumers Union Short Course (CUSC), ISO 3888 Part 2, Ford Path Corrected Limit Lane Change (PCL LC), and Open-Loop Pseudo Double Lane Changes are discussed. Details regarding the NHTSA J-Turn, and the three fishhook maneuvers are available in “Volume 1” [2].

Phase IV of the National Highway Traffic Safety Administration's (NHTSA) rollover research program was performed in 2001, starting in the spring and continuing through the fall. The objective of this phase was to obtain the data needed to select a limited set of maneuvers capable of assessing light vehicle rollover resistance. Five Characterization maneuvers and eight Rollover Resistance maneuvers were evaluated [1]. This paper is “Volume 1” of a two-paper account of the research used to develop dynamic maneuver tests for rollover resistance ratings. Test procedures and results from one Characterization maneuver (the Slowly Increasing Steer maneuver) and four Rollover Resistance maneuvers are discussed (the NHTSA J-Turn, Fishhook 1a, Fishhook 1b, and Nissan Fishhook). Details regarding NHTSA's assessment of the Consumers Union Short Course (CUSC), ISO 3888 Part 2, Ford Path Corrected Limit Lane Change (PCL LC), and Open-Loop Pseudo Double Lane Changes are available in “Volume 2” [2].

This paper covers research conducted at the National Highway Traffic Safety Administration's Vehicle Research and Test Center (VRTC) examining the performance of semitrailer anti-lock braking systems (ABS). For this study, a vehicle dynamics model was constructed for the combination of a 4×2 tractor and a 48-foot trailer, using TruckSim. ABS models for the tractor and trailer, as well as brake dynamics and surface friction models, were created in Simulink so that the effect of varying ABS controller parameters and configurations on semitrailer braking performance could be studied under extreme braking maneuvers. The longitudinal and lateral performances of this tractor-trailer model were examined for a variety of different trailer ABS controller models, including the 2s1m, 4s2m, and 4s4m configurations. Also, alternative controllers of the same configuration were studied by varying the parameters of the 2s1m controller.

This paper discusses dry stopping performance comparisons of various foundation brake systems on Class-8 truck tractors (having a GVWR greater than 33,000 lbs.). For these studies, four configurations of foundation brakes were fitted to two modern 6x4 conventional truck tractors without modification to the control, application, or ABS systems. Foundation brakes compared include standard S-cam drum brakes on all six positions, high-output S-cam drum and then air disc brakes on the steer axles, and air disc brakes on all six brake positions. Discussions include analyses of stopping distance from 60 mph (96.6 kph) for all test conditions. The truck tractors were tested in two weight configurations, LLVW (i.e., bobtail) and GVWR (50,000 lbs. total axle weight, using an unbraked control semitrailer).

The automotive safety community has grown increasingly aware of the societal costs of injury impairment and disability resulting from automobile accidents. A significant portion of this impairment can be attributed to lower extremity trauma. An accident data study was conducted to determine lower extremity injury frequencies and mechanisms for restrained front-seat occupants in frontal collisions. A query of the 1988-1990 NASS (National Accident Sampling System) data provided information on pelvis, femur, knee, leg, and ankle and foot injuries. Age, gender, seating position, and delta-V were examined for their effect on the data. Lower extremity injury data were compared with injury data of similar severity (AIS ≥ 2) for the head, chest, thorax, and abdomen. The NASS data was supplemented with injury impairment information which, combined with anthropomorphic and biomechanical data, provides a prioritization scheme for the design of dummy lower extremities and instrumentation.

Development of improved dummy lower extremities which are compatible with both the Hybrid III design and with other advanced torso designs is continuing. The first task was to establish the design and performance requirements for these new crash dummy components. To achieve this, an extensive literature review of relevant biomechanical studies was carried out and a detailed accident investigation of crashes involving lower extremity injury was performed. Finally, detailed discussions were conducted with biomechanical and clinical experts. The innfromation gained through these efforts was synthesized into a detailed set of design goals and requirements for the improved lower extremities, which are summarize in this paper.

This paper summarizes the results of research conducted by the National Highway Traffic Safety Administration (NHTSA) to determine how changing vehicle design parameters influence child restraint performance. Initial research consisted of surveying late-model vehicles' interior design characteristics as they pertain to child restraint systems. The next step involved dynamic evaluation of booster seats with respect to injury/excursion criteria measured on child test dummies under conditions which illustrated the changing vehicle design characteristics. Belt-positioning booster seat tests were conducted to evaluate the effect of belt type (lap/shoulder belt vs lap only belt) on seat performance. Differences in small-shield booster behavior when used with lap only belt or laplshoulder belt combinations were established in another series of tests. Another study demonstrated how varying seat back rigidity changed small-shield booster test results.

The National Highway Traffic Safety Administration has initiated research to develop performance specifications for dummy-based accelerometers in the crash test environment, and to provide criteria for defining and establishing equivalent performance among accelerometers from different manufacturers. These research efforts are within the general guidelines on transducer equivalency outlined in the current revision of the Society of Automotive Engineers recommended practice, Instrumentation for Impact Test, SAE 211/2 March 1995. Representative data from vehicle crash and component level tests have been analyzed to determine the acceleration levels and frequency content in a realistic dynamic environment for dummy-based accelerometers.

A study of the National Accident Sampling System (NASS) found an increase in upper extremity injuries when drivers were restrained by a seat belt and air bag as opposed to a seat belt alone. These injuries were attributed to forces from the air bag deploying or the air bag projecting the arm into vehicle components or the upper body of the driver. Two evaluation methods were used to assess the extent of injury and aggressiveness of different driver side air bags. The RAID, developed by Conrad Technology, and the Hybrid III instrumented arm, tested at the Vehicle Research and Test Center, were used in static testing to evaluate the effect of air bags on the arm. The positions of the RAID and the Hybrid III arm simulated the arm in four different turning positions with the forearm across the center of the wheel. Both devices recorded arm moments and accelerations. Film analysis determined the cause of the peak resultant moment for each bag in the four configurations.

In support of NHTSA's studies of heavy truck brake types and their effects on vehicle stopping performance and stability, the NHTSA Vehicle Research and Test Center (VRTC) has evaluated four foundation brake types on their Greening Brake Dynamometer. Several sample assemblies of each type of brake were tested to better understand variability. Braking tests were run under the “Laboratory Test Procedure for FMVSS 121D Air Brake Systems - Dynamometer” (TP- 121D-01) procedures. Afterward, the test scope was expanded to include higher speeds and higher severity conditions than those specified Test Procedure. This paper reports on the differences in braking effectiveness between two traditional S-Cam air brake types and two recently introduced Air Disc brake types. Burnish procedure trends are briefly discussed and compared. Responses of the pneumatic brakes to both constant-pressure and dynamic inputs are also compared and discussed.

In an effort to reduce the dry stopping distance required for heavy trucks, it is imperative to increase the effectiveness of the foundation brake systems. Where brakes are torque limited, increasing the brake output can be obtained by increasing brake size, chamber size, slack length, and friction of the braking materials. Looking just at the aspect of foundation brakes, the majority of current tractor and trailer brakes are of the S-Cam and Drum type. Two commercially available alternatives that produce higher output are Air Disc brakes and larger sized S-Cam brakes. Using one type, or a combination of these brakes (discs and drums on different axles) warrants a comparative study. The goal is to improve the effectiveness of the brake system, while maintaining or improving upon vehicle stability during braking. NHTSA's Vehicle Research and Test Center recently completed a brake test study of the effectiveness and stability characteristics of tractor and trailer combinations.