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1Â Â Roadway lighting is a widely recognized intervention for reducing nighttime crashes, but many research studies, warrants, and design practices overlook lighting in rural locations, especially at isolated intersections where lighting is used infrequently. To help provide a foundation for transportation departments considering if, when, and where to install lighting at isolated rural intersections, this synthesis was carried out to gather information and experiences from different agencies into a single document. A literature review and survey of state agencies were undertaken to identify common practices and gaps in existing knowledge. Of 51 state and district transportation departments invited to participate in the survey, 44 responded, a response rate of 86%. Among the findings from this synthesis are that isolated rural intersection lighting appears to be beneficial overall, but that predicting the benefits likely at a specific location is very difficult. Different transportation departments have different warranting criteria for identifying when and where to install rural isolated intersection lighting, but they all are based on similar factors such as traffic volume, night- time crash rates, and geometry of the intersections. However, it is not clear from the literature whether certain criteria are more beneficial to rural intersection safety. Some agencies use âdelineationâ lighting to notify drivers about the presence of a rural intersection, but an equal number of agencies do not use this practice, and the benefits of delineation lighting are not fully understood. Although there is general agreement that isolated rural intersection lighting can be beneficial, many agencies do not have sufficient information to quantify those benefits in financial terms so that lighting can be compared to other safety treatments through economic analyses. There is also a general lack of information about whether a regular maintenance schedule for rural intersection lighting would be beneficial over the more common practice of ad hoc maintenance, in which lighting equipment is replaced or repaired only after it is found to be damaged or burned-out. A few case examples of rural isolated intersection lighting in different states, as well as alternatives to lighting, are also provided. Research to address these knowledge gaps could help in developing consistent guid- ance for agencies and their contractors to follow when considering, warranting, and designing isolated rural intersection lighting. This synthesis document is designed as a resource for state and local transportation agency staff who wish to more systematically implement isolated rural intersection lighting where lighting will have the greatest potential effectiveness. S U M M A R Y Lighting Practices for Isolated Rural Intersections