Analysis of the injury severity of crashes by considering different lighting conditions on two-lane rural roads

  • Published: Journal of Safety Research 56: 2016: p 57-65
  • Authors: Anarkooli, A.J. & Hosseinlou, M.H.
  • Date Added: 08 Mar 2018
  • Last Update: 08 Mar 2018
  • Format: html


The research investigates lighting condition differences in the injury severity of crashes using 3-year (2009–2011) crash data of two-lane rural roads of the state of Washington.


Separate ordered-probit models were developed to predict the effects of a set of factors expected to influence injury severity in three lighting conditions; daylight, dark, and dark with street lights. A series of likelihood ratio tests were conducted to determine if these lighting condition models were justified.

Key Findings:

  • The modelling results suggest that injury severity in specific lighting conditions are associated with contributing factors in different ways, and that such differences cannot be uncovered by focusing merely on one aggregate model.

  • Key differences include crash location, speed limit, shoulder width, driver action, and three collision types (head-on, rear-end, and right-side impact collisions).

Practical Applications

  • The paper highlights the importance of deploying street lights at and near intersections (or access points) on two-lane rural roads because injury severity highly increases when crashes occur at these points in dark conditions.


Injury severity; Rural roads; Lighting condition; Ordered probit; Fixed effects