Study Details

Study Title: Safety Impact of Increased Traffic Signal Backboards Conspicuity

Authors: Sayed et al.

Publication Date: 2005

Abstract: Inconspicuous traffic signals is often cited as a contributing factor by drivers who are involved in collisions at intersections and as such, increasing the conspicuity of traffic signals can lead to improved safety performance. This paper describes a project that was undertaken to evaluate the safety impacts that are associated with improved signal conspicuity, and specifically improvements to the traffic signal backboards (backplates). This included the addition of yellow micro-prismatic retroreflective sheeting along the outer edge in an attempt to frame the signal heads and make them more visible to motorists. The evaluation included a time-series analysis to investigate the effectiveness of the traffic signal improvements on road safety performance at 17 signalized intersections. The study made use of comparison groups, prediction models and an Empirical Bayes analysis technique to account for the common confounding factors associated with road safety evaluation and to ensure that the results are reliable. This paper quantifies and describes how the addition of the yellow microprismatic retroreflective sheeting to traffic signal backboards at signalized intersections can provide cost-effective road safety benefits. The results indicated that the visibility improvements to the traffic signal backboards could reduce collisions by about fifteen percent.

Study Citation: Sayed, T., Leur, P., and Pump, J., "Safety Impact of Increased Traffic Signal Backboards Conspicuity." 2005 TRB 84th Annual Meeting: Compendium of Papers CD-ROM, Vol. TRB#05-16, Washington, D.C., (2005)


CMFs Associated With This Study

Category: Intersection traffic control

Countermeasure: Add 3-inch yellow retroreflective sheeting to signal backplates

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
0.85 15 4 Stars All All Not specified Urban