State of Practice Review: Human Factors Considerations for LED-Enhanced Static Traffic Signs

Abstract

Traffic signs communicate important information that drivers rely on to safely perform driving tasks. Because of their critical role, it’s crucial that drivers are able to detect, recognize, and respond to signs with sufficient time and distance to do so safely. When signs are difficult to detect or not easily distinguishable within a visually complex environment, drivers may miss critical information, which can compromise safe driving performance. As a result, enhancing sign visibility and conspicuity are key components in roadway and traffic control design.

There are a variety of treatments that can be implemented to improve sign conspicuity, including the use of retroreflective materials, the removal of unnecessary or redundant signs, and increases in sign size. In the early 2000s, light-emitting diodes (LEDs) were first introduced within static traffic signs to draw drivers’ attention to particularly important information (Bert, 2021).

From a human factors perspective, the effectiveness of LED-enhanced static signs depends on how drivers perceive, interpret, and respond to these visual stimuli under real-world driving conditions. This report explores literature on the use of LEDs within static signs, examines how their use relates to human factors principles, and describes current guidance and state practices regarding their implementation.