Street Lighting Design Solutions for Special Roads
Jul 30, 2026
Street Lighting Design is an essential component of urban transportation infrastructure. It directly affects the safety of nighttime driving and pedestrian movement, as well as overall traffic efficiency. This article focuses on various special road scenarios and provides detailed guidance on street lighting design standards and implementation considerations. The goal is to develop comprehensive and practical lighting design solutions tailored to real-world applications.
Lighting Design for Intersections
At a four-way intersection, luminaires may be arranged on one side of the road, in a staggered configuration, or symmetrically, depending on the specific road conditions and lighting requirements. Additional luminaires should be installed on the poles when necessary to meet roadway lighting requirements.
Large intersections may require supplementary lighting. This lighting can adopt either a conventional lighting arrangement or a semi-high-mast lighting system, while glare should be effectively controlled.
At a T-intersection, luminaires should be installed at the end of the terminating road, as shown in the figure below, to clearly define the road layout and structure.
Lighting at a roundabout should clearly illuminate the central island, traffic islands, and curbs. When conventional lighting is used, luminaires should preferably be installed along the outer side of the circular roadway, as shown in the figure below.
When the central island has a relatively large diameter, high-mast lighting may be installed on the island. Luminaires should be selected and pole locations determined based on the principle that the roadway luminance should be higher than the luminance of the central island.
Street Lighting Design Curved Road Sections
For curved road sections with a radius of 1,000 m or more, the lighting design may follow the same approach used for straight road sections.
For curved road sections with a radius of less than 1,000 m, luminaires should be installed along the outside of the curve. The spacing between luminaires should preferably be 50%–70% of the spacing used on straight road sections, as shown in the figure below. The outreach length of the luminaires should also be shortened accordingly.
On reverse-curved road sections, luminaires should preferably be arranged consistently along one side of the road. If this arrangement obstructs the driver's line of sight, supplementary luminaires may be installed along the outside of the curve, as shown in the figure below.
When the roadway is wide enough to require luminaires on both sides, a symmetrical arrangement is recommended. Particular attention should be paid to the placement of luminaires at the bend: they must not be installed on the extension of the luminaire alignment used on the straight road section, as shown in the figure below.
Overpasses and Underpasses
When conventional lighting is used, the illumination provided by the luminaires installed along the underpass should connect effectively with the illumination provided by the luminaires on both sides of the overpass. The average illuminance of the road surface beneath the bridge should be the same as that of the road surface outside the bridge.
Wall-mounted luminaires may be installed on the bridge columns, or luminaires may be mounted on the parapets beneath the bridge to provide lighting for the underpass.
The average illuminance uniformity of the overpass roadway should be consistent with that of the connecting roadways. Luminaires may be installed at the supporting structures of the overpass, or low-level lighting-such as parapet lighting-may be used to illuminate only the overpass roadway.
For large overpasses and underpasses, high-mast lighting may be used, with supplementary lighting provided for the underpass.
Street Lighting Design for Elevated Roads and Interchanges
The lighting levels of the upper and lower roadways should each be consistent with those of the connecting roads.
The upper roadway should preferably use conventional lighting. When it passes through a residential area, low-level lighting is recommended.
For the area beneath the bridge on the lower roadway, luminaires may be installed along the parapets on both sides beneath the upper bridge deck, or wall-mounted luminaires may be installed on the bridge columns to provide lighting for the lower roadway, as shown in the figure below.
The lighting level of ramps connecting to and from the bridge should not be lower than that of the roadway on the bridge. Conventional roadway lighting or low-level lighting may be used.
For elevated roads with multiple motor-vehicle lanes, parapet lighting should not be used as functional lighting when it is difficult to ensure adequate uniformity and glare control.
Street Lighting Design for Pedestrian Underpasses
Short, straight pedestrian underpasses with sufficient natural light may be equipped with nighttime lighting only.
For pedestrian underpass entrances and exits located in areas without nearby street lighting, dedicated lighting should be installed. The average horizontal illuminance on the steps should preferably be 30 lx, with a minimum horizontal illuminance of 15 lx.
Inside a pedestrian underpass, the average horizontal illuminance should preferably be 30 lx at night and 100 lx during the day. The minimum horizontal illuminance should be 15 lx at night and 50 lx during the day. Vertical illuminance should also be provided.
Pedestrian Overpasses
A pedestrian overpass crossing a road with existing lighting facilities does not necessarily require separate lighting. Where necessary, the height and installation positions of the streetlight poles adjacent to both sides of the overpass, as well as the configuration of the light sources and luminaires, should be adjusted according to the lighting requirements of the bridge deck.
Dedicated pedestrian overpass lighting should preferably be installed when the illuminance on the bridge deck is less than 2 lx or the illuminance on the stairs is less than 5 lx.
For pedestrian overpasses equipped with dedicated lighting, the average horizontal illuminance on the bridge deck should not be less than 5 lx. The stair illuminance should be increased accordingly. The ratio of the horizontal illuminance on the stair treads to the vertical illuminance on the risers should not be less than 2:1.
Lighting facilities on pedestrian overpasses should be designed to avoid causing glare to pedestrians or motor-vehicle drivers.
Street Lighting Design Pedestrian Crossings
The average horizontal illuminance at a pedestrian crossing should be no less than 1.5 times that of the roadway on which the crossing is located.
Vertical illuminance should be provided on pedestrians from the direction facing approaching vehicles.
Supplementary luminaires should preferably be installed at pedestrian crossings. Conventional roadway luminaires of the same type as those used on the adjacent motor-vehicle roadway may be installed near the crossing. Alternatively, directional narrow-beam luminaires may be installed above the crossing.
These luminaires should not cause glare to pedestrians or motor-vehicle drivers. Where necessary, dedicated shielding devices may be installed inside the luminaires, or the luminaire tilt angle may be adjusted to control glare.
A different type of light source from that used for the surrounding roadway lighting may also be used.
When decorative lighting is installed on buildings, structures, roadside trees, greenbelts, pedestrian overpasses, bridges, or grade-separated interchanges on either side of the road, it should not conflict with the functional road lighting or reduce its effectiveness. Decorative lighting and functional lighting should preferably be integrated into a coordinated design.
Conclusion
Following this Street Lighting Design for special-road can effectively eliminate nighttime lighting blind spots and visual interference. It can also improve the safety and comfort of nighttime travel on special urban road sections, helping create a standardized, efficient, and user-oriented urban road lighting system.
