Reconstruction techniques for energy-absorbing guardrail end terminals

Steel beam longitudinal barriers protect errant vehicles from roadside hazards; when impacted, they safely redirect the impacting vehicle and minimize the probability of serious injury. Guardrail end terminals are devices placed on the ends of longitudinal barriers and are frequently hit by vehicles that leave the roadway. Crash reconstruction is the effort to determine how a vehicle crash has occurred. Reconstruction is performed by several groups, including designers and testers of roadside safety devices so that they design and test for real-world conditions, and also by departments of transportation in order to determine appropriate warrants, maximizing the benefit–cost ratio for limited resources. This paper focuses on two items: first, the numerous types of energy-absorbing guardrail end terminals are identified and delineated and second, a crash reconstruction technique for determining the initial velocity of a vehicle impacting a guardrail end terminal based upon conservation of momentum and conservation of energy is developed. By understanding the types of guardrail terminals and being able to reconstruct real-world crashes, highway planners, designers and maintenance people will have significant more information than is currently available to aid in the goal of mitigating roadside crashes.