"Ran-off-the-road" fatal accidents currently account for approximately 65 percent of all freeway fatalities (1). Accordingly, ever-increasing emphasis has been given to the development of effective safety barrier systems, from guardrails to earth berms to median barriers to energy absorbing barriers and mires. However, highway designers have also recognized that safety barriers are hazards in themselves, misfits in the highway environment, and that they are items to be eliminated wherever possible. In a study of fatal accidents on the Interstate Highway System, it was found that fixed object collisions have been the leading source of fatalities, accounting for 43 percent of the 1968-1969 fatal accidents (2). Ironically, guardrails were found to be the most frequent objects struck first -- accounting for 31 percent of the total. Furthermore, this same study estimates that, excluding non-interstate and secondary urban roads, 6,300 miles of guardrail were constructed on public roads in 1969. Statistics such as these illustrate the risks facing today's drivers on the Interstate Highway System. Until a major modification is made that produces a significant reduction in such risks, less mobility (through travel restrictions) will be required to produce a significant reduction in fatalities per year (3).

Report Date


Report Number

No. 352

Digital Object Identifier



Presented to ASCE National Structural Engineering Meeting (April 24-28, 1972).