The Lighting Research Center (LRC) at Rensselaer Polytechnic Institute proposes to conduct a study, with support from the University Transportation Research Center (UTRC) and with cofunding from the LRC’s Transportation Lighting Alliance (TLA) industry partnership program, of brightness perception from transportation lighting systems used on vehicles, and along roadways and other facilities. The immediate objective is to elucidate the visual mechanisms underlying brightness perception under nighttime lighting conditions. This will be accomplished through a series of scale-model human factors experiments comparing the perception of brightness under lighting conditions differing in color. The second objective is to develop preliminary guidance for transportation agencies in U.S. Department of Transportation (USDOT) Region 2 that can benefit from these findings by utilizing light sources that optimize the visual benefits of lighting against the initial and operating costs of lighting (equipment, energy and maintenance). This will be accomplished through technical analyses comparing spectral properties of light sources for transportation systems, along with their luminous efficacy to provide recommendations for tailoring light source spectra that meet driver and pedestrian needs while maximizing energy efficiency.