The road construction is always indispensable to the development of a city, and the lighting is the most important part. The road and any hazards must be easily recognizable, and any pedestrians or cyclists must be visible. ANSI/IESNA RP-8-14 addresses the illumination of roads based on the following criteria: type of road material, roadway use, and pedestrian conflict classification.

This example shows a local road in a medium-density residential area where the pedestrian traffic is medium. The road material is concrete. There are two lanes for traffic with a total width of 20 ft and a 6 ft wide, shared use sidewalk on either side. Using this criteria, we find that the recommended average illuminance level on the roadway is 0.5 fc. On the sidewalk the recommended illuminance level is 1.0 fc, with a vertical illuminance level of 0.1 fc. Urban Roadway The fixture used is an LED area/roadway pole-top luminaire, used with an 18 ft pole. This fixture features a type II distribution, which covers the entire area width, and allows for wide spacings between fixtures. Precise reflectors create a light spread that is exceptionally uniform. The poles are spaced 100 ft apart, so that the minimum light level between fixtures does not fall below 0.1 fc, and the average illuminance on the roadway is maintained at 0.5 fc.

The bird’s eye view clearly shows the light distribution on the road. The darkest place on the road between the luminaires is 0.1 fc. The transition to this level, proceeding from the brightest point directly in front of the luminaire (1.5 fc), is done gradually and uniformly. The top image shows that the fixture is full cutoff; that is, all light emitted by the fixture is projected below the horizontal plane.