ISTEA required that FHWA: (1) determine whether vans, mini-vans, pickup trucks, and 4-wheel drive vehicles (light trucks) have impact behaviors different from the previously tested passenger vehicles, and (2) assess the adequacy of current design guidelines and standards for roadside features (barriers & safety appurtenances). These features include traffic barriers, crash cushions, terminals, truck-mounted attenuators, breakaway supports, cross-sectional elements, and terrain. There has only been limited research on the safety performance of light trucks for several reasons. One reason is that until recently, crash testing for roadside features only required the use of passenger cars. Another reason is the relatively recent emergence of many types of light trucks for use primarily as passenger vehicles. A final reason is that only in the last few years have accident data become available to permit the detailed study of vehicles in this class. The research that has been undertaken suggests, however, that: (1) a higher fatality rate exists for some run-off-the-road accidents involving light trucks, (2) higher centers of gravity may result in a greater propensity to roll over during or after interaction with a roadside feature, and (3) this class of vehicles represents more than 25% of the fleet and may grow to represent one-third of the vehicle fleet. Research is needed to evaluate the safety performance of current roadside features for light trucks. Specifically, the need exists to (1) determine which combinations of roadside features and subclasses of light trucks represent the greatest potential for safety problems, and (2) to assess the adequacy of current standards and guidelines for the design, placement, and testing of roadside features for light trucks.
The objectives of this research were to (1) evaluate current information on the safety performance of roadside features for each subclass of light trucks, (2) assess the significance of gaps in safety performance information, and (3) recommend priorities for future research, testing, and development needed to ensure that roadside features accommodate light trucks.
To accomplish the objectives, the following tasks were accomplished: (1) Review information on the performance of roadside features with each subclass of light truck vehicle. Include data from sources such as crash tests, accident studies, in-service evaluations, simulation, insurance claim experience, and so on. Contact transportation agencies, knowledgeable professionals, and highway safety advocates to identify relevant experience and anecdotal evidence. (2) Identify all types of vehicles in the light truck class that may constitute a significant portion of the vehicle fleet in the United States within the next 10 years and define subclasses appropriate for this research. For each subclass, define the range of static and dynamic properties and vehicle dimensions required for the evaluation of its safety performance relative to roadside features. (3) Identify specific roadside features for study in this project. Emphasis should be given to features commonly found or presently being installed in significant quantities. (4) Identify appropriate factors for the evaluation of safety performance considering accident frequency and severity, the criteria in NCHRP Report 350
, and other factors. Develop a scheme for comparison of the selected safety performance factors over the range of roadside features and subclasses of light trucks. Use existing information on the safety performance of passenger cars relative to the roadside features as a benchmark in the comparisons. (5) Conduct preliminary comparisons of safety performance for the various subclasses of light trucks using readily accessible data and analysis methods to generate inferences as to where the most critical problems exist. These comparisons can be based on the analysis of crash data, accident records, simulation results, or other information. (6) Prepare an interim report that describes the vehicles and roadside features identified, presents the results of the preliminary comparisons, and outlines a detailed work plan(s) for further evaluations of the safety performance of roadside features for each of the subclasses of light truck vehicles. Meet with the project panel to discuss the results and to select the roadside features and vehicle types that will be the focus of the subsequent tasks. (7) Conduct the data collection, manipulation, and analysis efforts outlined in the approved work plan as necessary to verify the preliminary analyses and to fill gaps in existing information about safety performance of roadside features with the various subclasses of light trucks. Document the sources of information and the procedures used in this effort for possible future use. (8) [added task] Conduct crash tests to determine the relative crashworthiness of various subclasses of the light truck group. (9) Synthesize the findings to provide a basis for recommendations for future research, crash testing, and development of roadside features to accommodate vans, mini-vans, pickup trucks, and 4-wheel drive vehicles. Recommend priorities for research and development efforts to address the most critical safety issues, and assess the adequacy of design standards and crash-testing procedures for this vehicle class. (10) Prepare a final report that describes the entire research effort.
: The project has been completed.
Product Availability: NCHRP Report 471