Guardrail end accident analysis (FHWA-OK-92-09) 2190

Abstract

This study documented attributes associated with guardrail end accidents on Oklahoma Department of Transportation (ODOT) roadways. The database which the researchers studied included accidents at a variety of guardrail end types, but most ends were either exposed or turned-down. The s everity of exposed and of turned-down guardrail end accidents in relation to lateral location of the guardrail, to vehicle rolling and vaulting, and to vehicle weight was investigated. Each acc ident report was read carefully to obtain relevant information for analyses. The results showed that on divided roads, vehicles struck median guardrail ends as often as right-side ends. On undivided roadways, right-side ends were struck 60% of the time. Fatalities or incapacitating injuries occurred in 1/6 of the end accidents. The vehicle vaulted or rolled in about 1/4 of the guardrail end accidents. The research indicated that turned-down guardrail end accidents had more vehicle rolling and/or vaulting than did exposed end accidents. Driver inattention was a factor in 1/3 of all guardrail end accidents. The majority of guardrail end accidents on the state system occurred on a small portion of the system, namely the higher volume roadways. The researchers sugge sted that accident reporting methods be enhanced, and that rumble strips be tested as a means to reduce guardrail end strike accidents. If newer, more expensive end treatments were installed, locating the new guardrail ends on a small portion of the system could address a maj ority of the end accident sites.