Study Details

Study Title: To Illuminate or not to illuminate: Roadway lighting as it affects traffic safety at intersections

Authors: Bullough et al.

Publication Date:DEC, 2012

Abstract: A two-pronged effort to quantify the impact of lighting on traffic safety is presented. In the statistical approach, the effects of lighting on crash frequency for different intersection types in Minnesota were assessed using count regression models. The models included many geometric and traffic control variables to estimate the association between lighting and nighttime and daytime crashes and the resulting night-to-day crash ratios. Overall, the presence of roadway intersection lighting was found to be associated with an approximately 12% lower night-to-day crash ratio than unlighted intersections. In the parallel analytical approach, visual performance analyses based on roadway intersection lighting practices in Minnesota were made for the same intersection types investigated in the statistical approach. The results of both approaches were convergent, suggesting that visual performance improvements from roadway lighting could serve as input for predicting improvements in crash frequency. A provisional transfer function allows transportation engineers to evaluate alternative lighting systems in the design phase so selections based on expected benefits and costs can be made.

Study Citation: Bullough, J.D., E.T. Donnell, and M.S. Rea. "To illuminate or not to illuminate: Roadway lighting as it affects traffic safety at intersections." Accident Analysis and Prevention, Vol. 53, pp. 65-77, 2012

Related Citations: (1) Donnell, E.T., R.J. Porter, and V.N. Shankar. "A Framework for Estimating the Safety Effects of Roadway Lighting at Intersections." Safety Science, Vol. 48(10), pp. 1436-1444, 2010 (2) Gross, F. and E.T. Donnell. Case-control and cross-sectional methods for estimating crash modification factors: Comparisons from roadway lighting and lane and shoulder width safety effect studies. Journal of Safety Research, Vol 42(2), pp. 117-129, 2011 (3) Bullough, J.D., E.T. Donnell, and M.S. Rea. "Roadway Intersections, Lighting and Safety." IMSA Journal, pp. 32-35, 60, Sept/Oct 2013


CMFs Associated With This Study

Category: Highway lighting

Countermeasure: Provide intersection illumination

CMF CRF(%)QualityCrash TypeCrash SeverityRoadway TypeArea Type
1.05-53 StarsDay timeAllNot specifiedAll
0.9283 StarsNighttimeAllNot specifiedAll
1.03-33 StarsDay timeAllNot specifiedUrban and suburban
0.9733 StarsNighttimeAllNot specifiedUrban and suburban
1.05-53 StarsDay timeAllNot specifiedUrban and suburban
0.9193 StarsNighttimeAllNot specifiedUrban and suburban
0.9823 StarsDay timeAllNot specifiedRural
0.9823 StarsNighttimeAllNot specifiedRural
1.09-93 StarsDay timeAllNot specifiedRural
1.07-73 StarsNighttimeAllNot specifiedRural