Metal Halide Light Towers: Mitigating Glare|
Of the several trends in construction taking place today, increasing the efficiency and safety of projects are usually the chief driving factors behind them. With the current shifting of operations such as road work towards nighttime hours occurring more and more frequently as companies and municipalities seek to lessen the impact these operations have on traffic flow and nearby businesses, lighting has become an increasingly important concern. Although shifting construction operations from daytime to nighttime hours offers the ability to relieve the impact of construction on traffic patterns and the flow of customers to businesses in the impacted area, performing operations at night increases the potential for loss of productivity and accidents. Providing sufficient illumination is then the critical factor to address when mitigating these potential problems.
There are several ways companies can maintain efficiency and safety during nighttime operations, chief among these being the addition of portable lighting equipment to the jobsite. The jobsite location and type of work being performed play important roles in determining the type of lighting to be used and how it is operated. The conditions around construction sites vary widely and any lighting equipment to be used must be chosen with these conditions in mind. Proximity to residences, traffic patterns, size of the work area, proximity of workers to traffic, and the type of work being performed all play pivotal roles in determining which lighting equipment is right for a particular application.
Of all the considerations to be kept in mind when selecting lighting equipment for the jobsite, safety of both the public and the workers involved in the projects should be of the most concern. No matter how a jobsite is illuminated, it must be kept in mind that this lighting is unnatural and every effort must be made to account for any unwanted effects this lighting may produce. Some of the most common projects performed during evening hours are those involving road and utility work. These operations often involve direct interaction with traffic and as a result any lighting used on the jobsite will have an impact on this traffic. Improperly chosen or operated jobsite lighting can have serious effects on the flow of traffic which may negate any benefits this lighting produces if not addressed when this lighting is used.
Among the problems that jobsite lighting may present, glare is the most predominant. Glare is basically defined as the discomfort or interference with vision, or temporary blindness caused by the eye being exposed to light levels exceeding those it has become acclimated to. As can be imagined, this is a serious problem for the driver operating a vehicle at night and approaching a work zone that is illuminated by artificial lighting. The lighting on jobsites tends to be very intense and very powerful because of the need to provide sufficient illumination for difficult and oftentimes hazardous operations. Although this light can effectively reduce the negative effects of nighttime operations on the productivity and safety of workers, unless properly installed and directed it can increase the possibility of traffic accidents and the jobsite injuries related to them. Glare is the most cited problem associated with these accidents and driver vision difficulties when approaching construction sites must be accounted for if lighting is to be both effective and safe.
The most common method of reducing the effects of glare from jobsite illumination is placing luminaries at extended heights above the job site. By placing lamps as high as possible they are removed from the driver’s direct field of vision as they approach the jobsite. Since glare occurs most often from direct visual observation of a light source, this is a generally effective tactic although this is a much simplified explanation of how height reduces glare. For more in-depth explanations of how glare can be described and reduced consult with your local DOT or the OSHA website for more information. Other methods of combating glare include installing supplemental hardware such as shields around lamps, diffusers, screens, and visors. Although these are sometimes helpful, they tend to lower lighting efficiency and limit light distribution, thus it is best if light positioning is done as effectively as possible to retain lighting efficiency and avoid the need for additional hardware.
For large jobsites it is usually best if the most powerful lighting equipment that is practical is used. Since reducing glare is largely dependent upon maintaining some considerable distance between the light source and the ground, more powerful lighting equipment will provide a greater degree of illumination despite this increased distance. Additionally, higher powered luminaries will reduce the number of lights required to illuminate a given area, reducing costs and the total amount of work area taken up by the lighting equipment itself. For large areas, high powered Metal Halide lamps are usually the most preferred type of lamp as they produce intense illumination that closely mimics the natural light spectrum produced by the sun. These types of lamps are often found used in equipment like Larson Electronics’s WCDE-6MHL mobile floodlight package and are capable of illuminating very large jobsites like those found in road work projects effectively and safely.
This type of mobile light tower setup provides 6,000 watts of illumination, enough to cover over 5 acres of work area. Since the unit is fully mobile it can be positioned wherever needed to help reduce the effects of the lights on traffic patterns while still providing effective illumination for the work area. With the ability to extend the light tower to 30 feet in height, glare is further controlled by moving the lamps themselves farther out of the approaching driver’s angle of view. Each Metal Halide lamp produces over 100,000 lumens of intense light, with six lamps in total for the unit. The result is over 600,000 lumens of light total produced, which is more than enough to maintain lighting efficiency even when the unit is extended to its full height. Light towers such as these demonstrate how powerful lighting can not only effectively mitigate the problems associated with performing construction projects during evening hours, but how it can do so safely as well.