Fixed roadway lighting systems increase night visibility, as well as improve safety, traffic movement, and general roadway use. Traffic volume, numbers of pedestrians, at-grade intersections, turning movements, signalization, and unusual geometrics are some elements that make lighting of streets and highways desirable. Lighting, in addition to its safety benefits, is a crime deterrent and a valuable aid to law enforcement agencies and often contributes to the pride of a community.
7.17.1 Warranting Conditions for Roadways Other Than Freeways [3]
It is not practical to establish specific warrants for the installation of roadway lighting to satisfy all prevailing or anticipated conditions. In general, lighting may be considered for those locations where the respective governmental agencies concur that lighting contributes substantially to the efficiency, safety, and comfort of vehicular or pedestrian traffic. Lighting may be provided for all major arterials in urbanized areas. It may also be provided for locations or sections of streets and highways where the ratio of night accidents to day accidents is higher than the statewide average for similar locations and a study indicates that lighting may be expected to significantly reduce the night accident rate. Determinations to install lighting that have been made on the basis of accident experience at a particular site can be applied to other similar highway locations. The latter should include similar geometric layouts on which experience or accident data are not available and also on highway sections where anticipated increase in vehicular and pedestrian traffic will present problems within a few years. Lighting may be considered at locations where severe or unusual weather or atmospheric conditions exist. In other situations, lighting may be considered where the local governmental agency finds sufficient benefit in the form of convenience, safety, policing, community promotion, or public relations to pay an appreciable percentage of the cost of, or wholly finance, the installation, maintenance, and operation of the lighting facilities [3].
Lighting has been successfully used on rural conventional highways at hazardous locations to reduce the number of accidents. Lighting of spot locations in rural areas
should be considered whenever the driver is required to pass through a section of road with complex geometry and/or raised channelization as well as at intersections with higher than normal accident rates [3]. Isolated lighting of railroad grade crossings has been used to help the driver identify when a train is present in the crossing.
As with any roadway or intersection, warranting conditions should also be applied at a roundabout to determine the need for lighting. If lighting is warranted, the roundabout should be lit to a level that is 1.3 to 2 times the values used on the best lit approach and the uniformity should be 3:1 or better. The lighting should be extended a minimum of 400 ft (122 m) along each road connecting to the roundabout. Providing lighting that will provide good pedestrian recognition is an important issue. Placement of light poles 10 to 30 ft (3 to 9 m) before the crosswalk is recommended as a means of accomplishing this task [7].
