Findings suggest that the traditional highway flare, despite its inherent risks, was found to be highly visible and scored well during testing in all scenarios. They continue to be viewed as one of the most cost efficient options for first responders. The chemical and electric flares tested were less visible than the highway flare when deployed at ground level. However, when elevated to a 36-inch height above the ground, their visibility scores increased dramatically and they were visible at a distance of 1 mile. The most effective and visible cone and flare combinations were those that were basic in design. Traditionally, law enforcement has utilized magnesium-based highway flares to identify accident locations and construction sites. These devices burn at high temperatures and create substantial risk of igniting combustible material or causing injury to the officer. Other problems with traditional highway flares are the potential environmental impact they have on soil and water. This research project supported by the U.S. Department of Justice, National Institute of Justice starts with a literature review which serves to present a brief background on the use of various portable traffic control devices, theories associated with their use, and specific environmental concerns that may arise from their deployment. The research study utilized a standardized visibility measure that was designed to compare the different flares and related traffic control devices. Figures, tables, and references