Citation

Elvik R, Ulstein H, Wifstad K, Syrstad RS, Seeberg AR, Gulbrandsen MU, Welde M. Accid. Anal. Prev. 2017; 108: 285-296.

Affiliation

NTNU, Norwegian University of Science and Technology, 7491 Trondheim, Norway.

Copyright

(Copyright © 2017, Elsevier Publishing)

DOI

10.1016/j.aap.2017.09.014

PMID

28934703

Abstract

This paper presents an Empirical Bayes before-after evaluation of the road safety effects of a new motorway (freeway) in Østfold county, Norway. The before-period was 1996-2002. The after-period was 2009-2015. The road was rebuilt from an undivided two-lane road into a divided four-lane road. The number of killed or seriously injured road users was reduced by 75 percent, controlling for (downward) long-term trends and regression-to-the-mean (statistically significant at the 5 percent level; recorded numbers 71 before, 11 after). There were small changes in the number of injury accidents (185 before, 123 after; net effect -3%) and the number of slightly injured road users (403 before 279 after; net effect +5%). Motorways appear to mainly reduce injury severity, not the number of accidents. The paper discusses challenges in implementing the Empirical Bayes design when less than ideal data are available.

Copyright © 2017 Elsevier Ltd. All rights reserved.

Language: en

Keywords

Before-after; Empirical bayes; Motorway; Road safety