Safety effects of traffic lane and shoulder widths on two-lane undivided rural roads: A matched case-control study from Norway

Petr Pokorny,Jan K Jensen,Frank Gross,Kelly Pitera

doi:10.1016/j.aap.2020.105614

Abstract

This study estimates the effects of lane and shoulder widths on occurrence of head-on and single-vehicle accidents on rural two-lane undivided roads in Norway while considering the differences between winter and non-winter accidents and their severity levels. A matched case-control method was applied to calculate the odds ratios for lane and shoulder width categories, while controlling for the effects of AADT and adjusting for the effects of region, speed limit, segment length, share of long vehicles in AADT and horizontal alignment. The study used a sample of 71,999 roadway segments identified in GIS and 1886 related accidents recorded by the police in five-year period. The results suggest that it is relevant to consider winter and non-winter accidents as well as severe and slight accidents separately when studying the effects of lane and shoulder widths on the occurrence of head-on and single-vehicle accidents. When examining lane and shoulder widths for all related accidents, the lane widths 1.50–2.50 m and shoulder widths 0.50−0.75 m were relatively safer than other categories on Norwegian two-lane rural undivided roads.

Highlights

This study looks at the effects of cross-sectional elements’ widths on the occurrence of head-on and single-vehicle accidents on rural two-lane undivided roads in Norway
The most common combinations of shoulder and lane widths in the sample are those with lane widths between 2.50–3.25 m and shoulder widths up to 0.50 m
The shoulder width 0.00−0.25 m and lane width 2.76−3.00 m were selected as the reference categories

Summary

Introduction

This study looks at the effects of cross-sectional elements’ (lane and shoulder) widths on the occurrence of head-on and single-vehicle accidents on rural two-lane undivided roads in Norway. These roads comprise a major portion of the Norwegian public road network. This road type carries a higher level of accident risk than do other types of roads (Gooch et al, 2016). The majority (83%) of these segment-related accidents were categorised by police as single-vehicle (n = 3956) and head-on accidents (n = 1537). Trucks have been frequently involved in fatal head-on and single-vehicle accidents (Langeland and Phillips, 2016)

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Conclusion