Internal vs. External On-Premise Sign Lighting : Visibility and Safety in the Real World.

University Transportation Centers Program2009PDFTech ReportGarvey, Philip M.Pietrucha, Martin T.Damin, SteveDeptuch, DamianThomas D. Larson Pennsylvania Transportation InstituteMid-Atlantic Universities Transportation CenterUnited States. Department of Transportation. University Transportation Centers (UTC) ProgramUnited States. Department of Transportation. Research and Innovative Technology AdministrationUnited States Sign CouncilThomas D. Larson Pennsylvania Transportation InstituteUnited StatesPennsylvaniaSignsVisibilityHighway safetyLightingIlluminated traffic signsResearch HubIlluminated commercial signsinternally illuminatedexternally illuminatedsignlighting designHighwaysSafety and Human FactorsAccidents and the Human FactorPSU-2008-02IUCRA 105569DTRT07-G-0003Bertucci, Andrew;Poorly visible on-premise commercial signs have been associated with reduced safety, as drivers trying to locate and make sense of these signs may drive slower than the rest of traffic and perform erratic, last-second maneuvers. One of the main reasons for reduced sign visibility is poor sign lighting. In addressing this issue, past research sponsored by the United States Sign Council Foundation demonstrated that internally illuminated on-premise signs have 40 to 60 percent greater visibility than externally illuminated signs in a controlled test track environment. Even so, an ever-increasing number of jurisdictions are implementing sign ordinances that prohibit the use of internally illuminated on-premise signs, mainly for aesthetic reasons. The objective of this research was to expand on the earlier test track research by evaluating the relative visibility of internally and externally illuminated signs on open roads in the real world. The results of this research clearly demonstrate the superiority of internally illuminated signs across a wide variety of driving conditions, sign offsets, sign sizes, shapes, colors, external lighting designs and quality levels127