Adequate roadway lighting allows better driver visibility during nighttime conditions. Research studies show that lighted roadways on average experience 28 percent fewer vehicles crashes on all roadway types. Most state DOTs have historically used High-Pressure Sodium (HPS) lights for their roadside lighting programs due to their wide availability and relatively low purchase costs. However, the short lifespan of HPS results in frequent replacement, leading to high life cycle costs. Light-Emitting Diode (LED) lights consume less energy, demonstrate improved performance, and require less overall maintenance due to their longer lifespans. Over time, this translates into maintenance cost savings for stateDOTs. In recent years, several state and local governments have begun increasing their use of LED lighting. KTC reviewed other state’s best practices for roadway lighting and assisted KYTC with analyzing the performance differences between HPS and LED. KTC also compiled a statewide roadside lighting inventory through coordination with each KYTC district.After developing the full inventory, the research team conducted light surveys at locations across Kentucky. The light surveys confirmed that LED lights routinely outperform HPS lights. It is recommended that Kentucky continue to transition to LED lighting, find a method for keeping the statewide lighting inventory up to date, and specify light spacing for new installations.

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© 2018 University of Kentucky, Kentucky Transportation Center

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The contents of this report reflect the views of the authors, who are responsible for the facts and accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the University of Kentucky, the Kentucky Transportation Center, the Kentucky Transportation Cabinet, the United States Department of Transportation, or the Federal Highway Administration. This report does not constitute a standard, specification, or regulation. The inclusion of manufacturer names or trade names is for identification purposes and should not be considered an endorsement.