Citation

Barbaresso JC, Bair BO. Transp. Res. Rec. 1983; 923: 90-97.

Copyright

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

DOI

unavailable

PMID

unavailable

Abstract

Previous studies regarding the accident implications of shoulder width have been inconclusive and their results contradictory. Engineering guidelines concerning shoulder width have been established, but emphasis is placed on the minimum shoulder width necessary for emergency parking and not on the effects of shoulder width on accident experience. The accident implications of shoulder widht on two-lane roadways in an urban county in Michigan are investigated. Some liability claims against the county road agency have alleged that shoulders, which are at variance with shoulder-width guidelines, are hazardous because they do not adhere to the suggested guidelines. One intent of this paper is to determine whether these allegations are substantiated. Analyses were performed to determine whether there is a significant difference in accident frequency between two-lane roadways that meet shoulder-width guidelines and those that do not meet the guidelines. The results of this research do not support the premise that roadways with wider shoulders have significantly fewer accidents than roadways with narrow shoulders. No significant difference in accident frequency was found between roadways that meet shoulder-width guidelines and those that do not meet the guidelines. Accident data reviewed in this study reveal that shoulder width is not not related to the frequency of overturn accidents, head-on type accidents, or to accident frequency in general, even after traffic volume and other variables are considered. A relation was discovered between the frequency of fixed-object accidents and shoulder width, but the findings indicate that fixed-object accident frequency is significantly lower on roadways with shoulders less than 7 ft wide than it is for roadways with wider shoulders. It was concluded from this research that (a) projects to reduce accident frequency should focus on factors that exhibit greater influence on accident frequency than does shoulder width; and (b) although it is desirable to adhere to current guidelines wherever possible, when undertaking certain types of construction projects it may be acceptable to retain existing shoulders of less than 8 ft in width unless a review of accident data for the project location indicates otherwise.

Language: en

Keywords

ROADS AND STREETS; HIGHWAY ACCIDENTS - Analysis