Developing the crash modification model for urban street lighting

Urban street lighting is one of the effective measures to reduce the road crash frequency. In this research, it was tried to determine the crash modification factor for urban street lighting by considering the effective factors in crashes such as lane width and number of lanes, and then, the relationship between this factor and the intensity of light was obtained as a crash modification model. The cross-sectional observational evaluation method was used to determine the safety effectiveness of lighting in urban roads. The results of both negative binomial and zero inflated negative binomial models were used because of high-level observations of zero values in the years studied. The variables used for modeling were a combination of geometric and functional characteristics of the arterials. The amount of CMF obtained by the ZINB model, in the case where the brightness variable was considered as a binary variable, was equal to 0.68. In addition, the relationship between CMF and average light intensity with regard to brightness as a continuous variable shows that if the standard value of the illumination intensity of 13 lx is set in the model, the CMF value of 0.20 would be earned for urban street lighting projects.