Screening needs for roadway lighting by exposure assessment and site-parameters

Current screening methods that assess the potential for roadway lighting to decrease nighttime crashes have not been updated since the 1970's. The existing methods dilute the influence of important factors and are inadequate for roadways where crash histories are unavailable. In this effort a two-part method for the screening of needs for roadway lighting is developed. First, an exposure assessment describes individual and population exposures to crashes, comparing projects by night-to-day crash rate ratios and traffic volumes. Outcomes of exposure assessment are based on potential crash reductions and costs of available lighting technologies. Second, a site specific analysis applies a set of eight engineering factors that suggest lighting would have benefit. Night crash histories on over eighty unlighted sections in three regions of Virginia are collected and studied in testing of the method. The effort has importance across transportation systems for screening of needs for visibility improvements.