This paper summarizes a study on the use of encapsulated• lens reflec· tive sheeting on overhead signs without external illumination. The ex· isting signs on the Interstate end many primary highways in Virginia were inventoried to determine the percentage of them that would meet the criteria for visibility· recognition distance so that their illumination could be eliminated if they we~ e refurbished with encapsulated· lens sheet· Ing. The plans for several proposed sign· lighting projects were also reviewed for the same criteria. Data relative to the installation, energy, and maintenance costs for ligh1ing overhead signs were also collected. It was concluded that Illumination could be eliminated on approximately 45 percent of the existing signs encl 50 percent of the proposed ones. The anticipated benefits include monetary and energy savings, reduction in the exposure of maintenance personnel to hazardous working con· tions. end improved services to motorists.

The brightness of encapsulated-lens (high-intensity) reflective sheeting is superior to that of the enclosed-lens sheeting that is presently used on overhead b: affic signs (1, 2, 3, 4). Consequently, the performance of this materiarwas evaluated by the Virginia Department of Highways and Transportation (VDHT) to determine the feasibility of using it on overhead signs without illumination, and it was concluded that the use of encapsulated-lens sheeting would allow the elimination of U1e external lighting on many overhead signs without adversely affecting the service to the motoring public (5). Subsequently, a joint study teamfrom the Office of Engineering and Traffic Operations and Research and Develol? ment of the Federal Highway Administration (FHWAJ evaluated the performance of encapsulated-lens sheeting in five states (6), and the FHW A removed the use of encapsulated-lens sheeting from the experimental category and established guidelines for the elimination of external lighting on overhead guide signs that are made with encapsulated-lens material. The use of encapsulated-lens sheeting and the elimination of lightiJlg on many overhead signs should be advantageous to many transportation agencies. Intuitively, the benefits would appear to include moneta. i· y savings, energy conservation, increased safety for maintenance 1Jerson11el, and improved service to motorists. However, the consideration of these probable benefits generates questions such as the following: What percentage of the signs in Virginia meet the criteria for the elimination of lighting? What is the installation cost for lighting? What is the energy cost for lighting an overhead sign? What is the maintenance cost for the lighting on a typical overhead sign?