Citation

Graham JL, Harwood DW. Transp. Res. Rec. 1983; 923: 72-86.

Copyright

(Copyright © 1983, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

Clear recovery zones outside the highway shoulder provide an opportunity for vehicles that leave the roadway to come to a safe stop or to return to the roadway. The results of a research effort to determine the effectiveness of clear recovery zones in reducing the number and severity of run-off-the-road (ROR) accidents ant to provide an approach for the cost-effective application of clear recovery zones are presented. Actual accident data were obtained and analyzed to compare three different roadside design policies: the 6:1 clear zone policy, the 4:1 clear zone policy, and the nonclear zone policy. Three highway types were also considered: two-lane highways, four-lane freeways, and four-lane divided nonfreeways. Road sections that had these highway types and roadside design policies were identified in Illinois, Minnesota, and Missouri. Analysis of the accident data for the study sections revealed that roadside design policy had a statistically significant relation to single-vehicle ROR accident rate for all of the highway types studied. The differences in the accident rate between roadside design policies were quantified for each highway type. An analysis of the severity of single-vehicle ROR accidents revealed that the severity distribution did not vary between the roadside design policies on any of the three highway types studied. Four design examples were developed in order to illustrate the cost-effectiveness implications of the safety effectiveness measures developed in the study. The examples compared the accident reduction benefits and typical construction costs for improving highways from one roadside design policy to another.

Language: en

Keywords

HIGHWAY SYSTEMS; HIGHWAY ENGINEERING; HIGHWAY ACCIDENTS - Analysis