Screening needs for roadway lighting

Screening methods that assess the potential for fixed roadway lighting to decrease nighttime crashes have not been updated since the 1970's. The methods dilute the influence of important factors, are inadequate for roadways where crash histories are unavailable, and lack a theoretical foundation. This thesis develops an evidence-driven method to aid engineers and planners in the screening of needs for fixed roadway lighting. Development of the method proceeds from principles of risk assessment and management that have been previously applied in diverse disciplines. First, an exposure assessment is developed to describe individual and population exposures to crashes. Needs are compared by night-to-day crash rates, measured directly or estimated indirectly, and traffic volumes. Outcomes of exposure assessment are identified based on potential crash reduction and costs of available lighting technologies. Second, a site parameters assessment is developed to identify a set of engineering factors that suggest lighting would be effective to reduce crashes. Literature review, classification of visibility-loss scenarios, and dialogue with engineers support the development of the site parameters assessment. In testing the method, night crash histories of over eighty unlighted sections in three regions of Virginia are collected and studied. A recommendation for future effort is to develop screening that distinguishes visibility technologies that are uniquely effective. The thesis has led to an initiative by the National Cooperative Highway Research Program to revise its existing screening method. Furthermore, the development of the thesis has general importance for screening and evaluation of needs for safety improvement in the variety of transportation systems.

Note: Abstract extracted from PDF file via OCR.