Reports on Higher-Conspicuity Warning and Regulatory Signs

Several regulatory sign materials have become available in recent years that improve the conspicuity of signs. These improvements include higher retroreflectivity for microprismatic materials that increase nighttime conspicuity, adding fluorescence that improves daytime conspicuity, and adding light emitting diodes (LEDs) in the sign face to improve daytime and nighttime conspicuity. 

Many statistically significant beneficial results occurred. In general, most of the signs resulted in at least a small reduction in speeds. 

Due to these beneficial results, recommendations for implementation of higher conspicuity sign materials have been split into three categories: 

  • Statewide implementation (maintenance replacement or new installations)
  • Spot implementation as needed, and
  • Optional implementation (either statewide or as needed)

The objective of this research project was to evaluate driver behavior in response to field installations of high-conspicuity materials on signs and signposts. These materials were installed at locations where it was believed that they would provide a significant benefit to traffic safety. One application can be implemented statewide immediately, seven applications can be implemented as special treatments, or on an as-needed basis, and three applications can be implemented as experimental devices by permission of the Federal Highway Administration.