Among contractors, there are those who prefer daylight operations and those who find evening hours to be a better fit. Evening operators cite less traffic, less impact on businesses, and the ability to reduce the number of overall complications associated with conducting large scale operations during times of peak traffic and pedestrian activity as motivating factors behind moving operations to evening hours. Although these are indeed excellent reasons to move roadway and building operations to evening hours, doing so creates additional issues that if not properly addressed, can negate any benefit to be gained.

Evening construction operations present unique challenges that arise primarily due to the lack of available ambient light. While during daylight hours we normally think very little about the role lighting plays in how we conduct our business, for contractors working outside, lighting can mean the difference between safety and productivity and a failed business. While operating at night is often a personal decision made by contractors, the stakes are more and more frequently being raised as many states have begun requiring the contractors working to build their bridges, roads and buildings to conduct operations at night in order to lessen the impact these operations have on the public. As a result, lighting has become a major issue for contractors seeking to maintain profitability while increasing safety.

Up to half the road work performed in the United States takes place at night. While this lessens the problems with traffic congestion and safety such activities pose for the public, the issues of safety and productivity are increased in importance for the contractors. As well as keeping work sites well lit in order to maintain productivity at optimal levels, contractors must also deal with motorists who may be under the influence or are easily distracted or confused by the bright lights of a construction site. Although there are many regulations in place to assist in setting standards and procedures for nighttime construction illumination, these can only go so far in assisting operators. Ultimately, it is up to the contractors to determine which lighting methods and equipment are best suited for their particular activities and implementing them wisely.

For most large scale road and building projects being carried out at night, high power light towers are overwhelmingly the systems of choice. Usually self powered by diesel generators and equipped with banks of high intensity metal halide lamps on the end of extendable booms, these systems can illuminate acres of property for many hours with little oversight. These metal halide light towers are quite effective, but due to their high power and tendency to use gas or diesel engines for power sources, require some forethought if they are to be used to their best efficiency and safety. Problems with exhaust fumes, glare, and very windy conditions can present serious problems if not taken into consideration, and before a contractor decides to erect light towers each should be addressed adequately.

Some of the most serious issues associated with the use of large light towers concern glare and dark spots. For drivers approaching a nighttime road construction project, the fast and extreme increase in brightness can be difficult to adjust to after miles of driving under relatively low light levels. This problem is exacerbated by light towers that are not properly adjusted to direct light onto the work site without creating glare for oncoming traffic. This problem is usually fairly easy to address if operators take the extra step of making a few passes in their own vehicles through the construction zone after light towers have been deployed in order to assess how accurately they have been placed and aimed. Glare can also be addressed through the inclusion of lamp diffusers and shields although these methods do incur a small extra cost, but one which is offset by the added security of well managed lighting.

As well as glare, dark spots and shadows can also present challenges that must be addressed in order to gain the most benefit from portable or mobile light towers. Dark spots most often occur when too much space is left between deployed towers and poor deployment and aiming is performed. To eliminate dark spots, towers need to be deployed with some allowance for overlap of the effective light beams. Additional improvement can be made by raising towers to their maximum heights in order to gain maximum area coverage. In the case of raising towers to their maximum heights, additional benefit is gained by a reduction in number and size of shadows that are cast as beam angle relative to height is also increased. An additional benefit of maximum deployment height is that the potential for glare encountered by oncoming traffic is also reduced as the increased tower height helps to move the light source above the driver’s direct line of vision.

When deploying towers for maximum effectiveness, operators should always be aware of how placement and height also affect the effective amount of illumination reaching the work area is affected. While increasing tower height does indeed improve coverage and reduce glare potential, it also reduces the intensity of the illumination reaching the work area. 5 foot candles of light reaching the work area is generally considered acceptable for general construction activities, while a minimum of 10 foot candles is required for areas where equipment and machinery is being operated. Although most heavy equipment and machinery carries its own general lighting in the form of headlights or small floodlights, these equipment lights are generally considered inadequate for fast paced operations, and nowhere near effective enough for ensuring the safety of workers operating near and around such equipment.

Overall, providing nighttime illumination on construction sites is anything but a simple matter of erecting a few towers. Consideration must be given to a wide range of factors including worker and public safety, the efficiency with which towers illuminate the workspace, and the overall amount of lighting required to perform operations without creating undue glare for traffic and pedestrians. In order to ensure maximum safety and productivity, operators should refer to OSHA, their local DOT, and state regulations regarding job site and construction lighting should they have any question about the suitability of any lighting equipment for the job at hand.