This study, sponsored by the Federal Highway Administration (FHWA) and conducted by ENSCO, Inc., used full-scale crash testing of small and large test vehicles to investigate the impact performance of inertial barrel and energy absorbing impact attenuator systems. Special emphasis was placed on impact performance of minicompact sedans. In all, 20 tests were performed: 16 with inertial barrels and 4 with an energy absorbing system. The 16 inertial barrel tests studied the effects of the following crash scenarios: large car versus small car, angled versus head-on positions, pea gravel versus sand fill material, frozen versus nonfrozen sand fill, loose sand versus bagged sand and two different brands of attenuator barrels. The four energy absorbing system tests used a six-bay Guard Rail Energy Absorbing Terminal (GREAT) system and studied the effects of head-on versus angled positions and large car versus small car impacts. All tests used instrumented dummies and all tests generated a National Highway Traffic Safety Administration (NHTSA) digital data tape. Results of the program showed large and small car performance to be generally acceptable when using NCHRP 230 and dummy analysis procedures. In one test (C-04) the large car exhausted the capacity of a sixbay GREAT system.

Past testing and analysis of impact attenuators has been based on vehicles weighing 2,250 pounds (1023 kg) or greater. Because of the recent increase in sales of minicars (1,800 lb, 818 kg, range), this class is becoming a significant portion of the vehicle population. This raises new vehicle collision concerns. The small size and weight of the mini cars reduces the dimensions of the wheel base, track width, and crush space, and lowers the mass moments of inertia when compared to larger cars. These differences affect the behavior of the car in a collision. To better understand the behavior of mini cars in impact attenuator collisions, a series of 20 full-scale crash tests were studied under a Federal Highway Administration (FHWA) contract entitied" Impact Attenuators-A Current Engineering Evaluation." For comparison, seven of the 20 tests were conducted with large cars. The major objectives of this project were as follows: