Section 6: Spacing of Light Poles

Standard Spacing for Freeways and Complete Interchange Lighting

For freeway lighting, TxDOT has standard spacings for conventional light poles to provide the minimum AASHTO-recommended illuminance levels. If higher light levels are needed, the spacing should be calculated with lighting design software.
50 ft. poles with 400W EQ LED luminaires may be spaced 270 ft. apart to provide the minimum recommended freeway illuminance levels. This will extend up to 60 ft. across the roadway from the luminaire. If wider roadways need to be lit, the spacing should be calculated with lighting design software.
40 ft. poles with 250W EQ LED luminaires may be spaced 220 ft. apart to provide the minimum recommended freeway illuminance levels. This will extend up to 50 ft. across the roadway from the luminaire. If wider roadways need to be lit, the spacing should be calculated with lighting design software.

Standard Spacing for Roadways Other than Freeways

To determine the required illumination levels for roadways other than freeways, use the tables in Section 2 of this chapter, the
AASHTO Roadway Lighting Design Guide
, or
ANSI/IES RP-8-14, Roadway Lighting
. An illumination program capable of calculating luminance or illuminance levels is required to determine if adequate illumination levels have been achieved.

Merge and Diverge Lanes

For partial interchange lighting, the first light pole for merge and diverge lanes should begin at the end of the weave area and continue to within 50 feet of the painted gore, as shown in Figure 6-2.
Typical placement for partial interchangelighting, 40 foot luminaire poles at merge and diverge lanes. (click in image to see full-size image)
Figure 6-2. Typical placement for partial interchange lighting, 40 foot luminaire poles at merge and diverge lanes.

Lighting Near Overpasses

Poles supporting lighting for roadways beneath overpasses should be placed at least 20 feet from the overpass to reduce glare on the overpass.

Determining Mounting Height

Mounting height depends on the number of lanes to be lighted. The designer must use the mounting height that allows for adequate illumination levels. If proper lighting cannot be achieved with one pole, the designer should consider using additional poles to provide proper coverage.