Rear Signal Lighting: From Research to Standards, Now and in the Future

Rear signal lighting on vehicles has two primary functions: informing other drivers about the presence of a vehicle on the roadway, and alerting those other drivers to intentions of a vehicle's driver before actions such as turning or stopping occur. In the present paper, reports, articles and other technical literature, pertaining to rear lighting signal system photometric requirements and use of dynamic display features, are reviewed. The objective is to synthesize recommendations for configuring rear lighting in order to optimize systems for different ambient weather and lighting conditions, dirt accumulation, and warning functions. Research results from European, North American and Japanese contexts are discussed. While consensus appears to be building that rear-lighting displays to communicate emergency-type stopping or slowing maneuvers would likely be beneficial, a feasible first step that could be undertaken in the near future is the development of new standards for modulating rear lighting intensity according to ambient conditions or dirt accumulation.