Chapter 8: Temporary LightingAnchor: #i999118
Section 1: Design and LayoutAnchor: #i999123
The purpose of temporary roadway lighting is to improve the ability of motorists to navigate the construction area.Anchor: #i999133
Difference Between Temporary and Work Zone Lighting
Temporary roadway lighting is not the same as work zone lighting. Work zone lighting is installed so that the contractor may work at night. If work zone lighting is installed, care should be taken to ensure that the visibility of passing motorists is not reduced below an acceptable level. Temporary roadway lighting helps reduce the negative effect of work zone lighting.Anchor: #i999143
Some special considerations affecting the design of temporary lighting include:
- cost of system
- ease of installation
- ease of maintenance
- ease of moving the temporary poles.
Because the purpose of temporary lighting is to make it safer to travel through the construction area, the lighting should be installed in such a way as to limit glare and avoid the placing of hazardous obstacles near the travel ways.
Roadway delineation should be considered along with any temporary lighting requirements.Anchor: #i999183
Types of Temporary Lighting
Some possible types of temporary lighting systems include:
- standard steel poles with or without breakaway bases
- wood poles, 30- or 40-foot mounting height, protected from traffic, with standard highway light fixtures
- short poles mounted on concrete traffic barriers with
low wattage delineator type lighting — examples include:
- 70 watt HPS wallpack type fixtures on 4 × 4 inch × 8 foot poles on top of or behind barriers
- rail mounted fluorescent fixtures
- floodlighting from just inside or outside of the frontage road
- permanent high mast illumination installed early in project.
Illumination levels should be higher than normal, where practicable, in detour areas, gore areas, and other construction zone obstacles (impact attenuators, etc.).
Illumination levels and uniformity may be lower than normally required in areas where the motorist has no special navigational decisions to make.
Lighting systems should not create excessive glare, a potential problem with low mounting heights.Anchor: #i999248
Electrical System Integrity
Electrical safety and integrity must be maintained in temporary lighting. Follow these guidelines:
- Where breakaway poles are used, breakaway electrical devices should also be used.
- Overhead wiring may be considered where non-breakaway poles are used.
- Voltage should not exceed 277 VAC to ground for temporary lighting units mounted at 18 feet or less.
- Portable cord or other temporary wiring may be used in lieu of buried conduit and conductor systems.
- It is sometimes cost effective to use permanent lighting service pole locations for the temporary system.
- Usually fused fixtures and non-fused breakaway disconnects are preferable for temporary lighting.
Placement of Light Poles
All poles located within the clear zone should be of the breakaway design or should be otherwise protected from vehicle impact (behind concrete barriers or guard rail). (See Chapter 6, Section 7, Pole Placement Guidelines, for more details.)Anchor: #i999302
If practicable, temporary lighting should be installed before the existing lighting is disabled.Anchor: #i999312
Plans and Specifications
Temporary lighting plans should show:
- the type and number of units required
- locations, spacings, and offsets of poles
- bracket and pole details
- electrical connection details, such as:
- electrical services
- conduit and wire or cord runs
- strain pole connections and guys (if used)
- breakaway disconnects (if used).
Temporary lighting should be coordinated with traffic control plans, which should show where and when the poles are to be placed or relocated.
Specifications for fixtures, wiring, poles, and services should be included with the plans when non-standard items are used. Ensure that circuit voltage drop is compatible with the ballasts of fixtures selected. Magnetic regulating ballasts are recommended, because they tolerate ±10 percent line voltage variation.