Intelligent control of roadway lighting to optimize safety benefits per overall costs

Although there is an increased awareness of roadway lighting control strategies that go beyond existing dusk/dawn switching, the implementation of new control strategies is seriously limited because there are few data to support when, where and by how much the roadway lighting should be adjusted. Two recent studies, one estimating nighttime crash reduction associated with roadway intersection lighting systems, and one characterizing the visual performance benefits of these same lighting systems, converge to produce a transfer function that enables roadway engineers to establish cost-effective control strategies for roadway lighting. Roadway lighting is associated with specific costs for equipment, operation and maintenance. The economic benefit of prevented nighttime crashes can also be quantified. Integrating these costs and benefits with the transfer function, the value of roadway intersection lighting is highest when traffic volumes are highest. Control schemes coordinated with hourly nighttime traffic volume data can be justified from simple payback periods of a few months.