This study was designed to determine the effectiveness of partial lighting (lighting that consists of a few luminaires located in the general areas where entrance and exit ramps connect with the through traffic lanes of the freeway) of interchanges and to develop recommendations for its use. This study concentrated on the benefits of lighting rather than on the costs, and crossroad lighting at the ramp terminals was not included. The study included a literature review, a questionnaire survey and analyses to isolate reasons for selecting or rejecting specific types of lighting and interchange designs, the variation of lighting warrants, and the availability of accident and traffic operational data and the results of analyses of the effectiveness of interchange lighting and traffic operations. The study found that 37% of the interchange lighting is complete interchange lighting (CIL) and 63% is partial interchange lighting (PIL). The study concluded that (1) CIL performs better than PIL to systems consisting of 1, 2, or 4 luminaires; (2) either CIL or PIL performs better than no lighting; (3) PILs with fewer luminaires one or two perform better than PILs with more luminaires (four); (4) there is a tradeoff between cost and traffic operations and safety factors in the design of freeway interchange lighting; and (5) existing CIL systems should not be reduced to PIL systems if traffic operations and safety (defined in terms of driver behavior measures) are important considerations.
Samenvatting