The purpose of this project was to provide an initial investigation into the effects of different light source correlated color temperatures (CCT) on detection and color recognition of roadway objects and pedestrians. This project included an investigation of both the light source spectrum from the overhead lighting spectrums as well as correlated color temperature from vehicle headlamps.

The detection of pedestrians and small objects along the roadway edge was measured on the Virginia Smart Road. Here the objects were located at specific points along the roadway and participant drivers performed a detection task. The point of first detection was recorded and the detection distance calculated. The objects appeared under high-pressure sodium (HPS) and light-emitting diode (LED) overhead lighting systems, as well as headlamps filtered to resemble LED and the amber overhead HPS sources.

The primary results from this investigation indicate that:​ 1) There is not a significant difference in terms of pedestrian detection and targets located immediately alongside the roadway between the correlated color temperature of the vehicle headlamps within the range selected ;​ 2) Overhead lighting is a significant factor in the detection and color recognition of pedestrian clothing, but results indicate that it is the intensity – not necessarily the color – of the lighting that makes it a significant factor;​

The tasks considered in this investigation were primarily foveal, meaning that pedestrians were within the line of sight of the driver. However, most spectral impact is expected to be in the periphery of the visual field. Part of this investigation considered the extent to which peripheral vision plays a role in object detection for a driver. Further investigation using a more extensive peripheral detection component is required to more fully explore the impact of the light source to the periphery.

As light sources transition to new technologies, light source spectrum is becoming a significant safety aspect of the roadway environment. The impact of the correlated color temperature of the headlamp is not significant in the foveal detection of pedestrians and objects within the range investigated. Further investigation of the peripheral impact of these light sources on pedestrian and driver safety is ongoing.