Shedding danger

Doug Dahlgren / June 11, 2009

Take a quick look around. Unless you’re somehow reading in the dark, you can see objects surrounding you, and it’s all thanks to an incredible phenomenon known as light.

Although it would be exceedingly difficult to function without it, light is a resource that is often taken for granted. Fluorescent office lighting, neon signs, a living room lamp and even the sun—we just don’t think about light that much, until we are without it. But utter darkness is not the only instance where a lack of light suddenly becomes quite noticeable.

Imagine a dentist performing a root canal with only room lights for illumination, or an accident victim being wheeled in for surgery at a hospital with ambience more fitting for a movie theater than an emergency room. Obviously, in reality, these situations dictate the use of far more light to ensure safety, as well as to simply make it possible to carry out such intricate procedures in the first place.

While the medical field has shown a clear understanding of the importance of high-quality lighting, this recognition does not always translate to construction projects and other jobsites that require lighting for nighttime work. Often workers are only supplied with enough light to “get by.” And that is surprising when you consider that both safety and productivity are absolute musts in these applications.

Some contractors just are not aware that there are real differences in light-tower performance from one model to the next, and to others it may not seem that portable light towers have changed all that much over the years. But manufacturers, in fact, have made great strides to introduce new technology such as greater and better light output, compact designs and other value-added features. It is all in the name of making jobsites safer and more efficient than ever before.

Brighter and whiter

There is no better evidence to demonstrate the improvements in light-tower technology than the upgrade in the performance of light produced. The evolution of jobsite lighting took a great step forward just a little more than a decade ago with the development of parallel lamp fixtures that were designed around the newly available BT37-size 1,000-W metal-halide lamp.

Until that time light towers employed the larger BT56-size lamps traditionally used for permanent applications such as warehouse and stadium lighting. But the size, weight and physical design of the BT56 lamp and existing fixtures did not make them conducive to surviving well in portable light towers. The BT37 lamp produced the same amount of light, but its smaller size provided an opportunity to develop a fixture specifically for mobile light-tower applications.

Most of the previously available commercial fixtures were of a coaxial design, typically the BT56 lamp surrounded by a spun aluminum reflector. In addition to being fairly large and susceptible to damage, coaxial fixtures also required the light produced by its lamp to be reflected by the luminare, resulting in a considerable loss in efficiency. Furthermore, one characteristic of universal metal-halide lamps was reduced light output if the lamps were mounted out of position. These lamps produced maximum illumination in the vertical position, but out of that position they would lose up to 18% of their output.

The BT37 allowed the creation of the parallel lamp fixture, which was more compact and less prone to damage. About half of the light produced could be projected directly through the lens, with only half of it reflected. And finally, the new lamp could produce near its maximum lumen output—97%—even when in a horizontal position. All of this added up to a fixture that provided a more even distribution of light and up to 30% improvement in performance and efficiency.

End users gain obvious advantages from the consistently high light output provided by parallel fixtures. One benefit is more light, which instantly provides better visibility and safety. Another is the ability to adequately light more square feet per light tower, which, in turn, can reduce the total number of towers needed to light the site. By minimizing the required number of towers, contractors can save money on purchases or rentals, as well as on transport costs to get lighting equipment to the jobsite, all while still supplying enough lighting to ensure safety.

Light performance continues to advance. In the past year, a new lighting technology was introduced that utilizes 1,250-watt lamps that produce 150,000 lumens per lamp—up 36% from the 110,000-lumen output of standard 1,000-watt lamps. The amount of light is one thing, but this technology also produces an improved color rendering index (CRI) of 70, compared with 65 CRI with typical metal-halide light.

Essentially, CRI measures the ability of a light source to faithfully reproduce the colors of objects as they appear in natural sunlight. A light tower’s higher CRI can therefore allow objects to be seen more clearly and true to life. This new light source also provides a whiter light with a higher color temperature to further optimize its effectiveness for visual tasks performed at night.

Because workers using this light source can better see other people, equipment and potential hazards as they truly are, the risks of minor operator mishaps or more serious accidents are diminished. This is particularly critical in applications where the work is more detailed and there is a smaller margin for error.

Just the simple fact that these workers can gain a better overall orientation in night environments also can assist with completing jobs more quickly. In short, the additional and improved light is a resource that can provide greater productivity and a much safer jobsite at the same time.

More compact

Light is not the only recent upgrade in light-tower technology. The physical makeup of towers has seen a positive change as well, with a more compact design being one such improvement. A light tower may not be immediately thought of as a piece of equipment that needs to be more compact. It typically does not take up all that much space on a jobsite. But when taking into account factors like shipping, transport and storage, the compact nature of a light tower can bring many benefits.

Examine traditional towers, where the light mast folds up when not being used and subsequently leaves the light fixtures themselves lying horizontally and overhanging the frame of the unit. This arrangement requires more square feet of space around the frame of the tower to accommodate the fixtures.

By contrast, new designs feature a mast that retracts by telescoping vertically in and out of its own housing rather than being folded over the top of the unit. This design keeps the light fixtures within the footprint of the tower, thus eliminating the need for added space around it when being stored or towed.

A contractor or rental center in the market for a fleet of light towers can net some quick savings with these compact towers during initial shipping. But even more money can be saved over the lifetime of a unit through reduced transport costs. Rather than making two trips to a jobsite to haul light towers, it may only take one trip. Rather than using three trucks for transport, the design of the towers may allow a contractor to haul them with just two trucks. In either case, the cost of transporting equipment is reduced simply by having a more efficiently designed light tower. And these savings repeat themselves any time towers must be moved.

And when the towers are not being moved, such as while sitting in a contractor’s lot or in a rental yard, their compactness also comes in handy. Without needing space to accommodate fixtures, compact towers can be placed closer together, reducing wasted space and allowing more room for other pieces of equipment—or even more light towers—to be stored.

Not only does a compact tower design save space, but it also reduces the chance of damage. When these fixtures overhang the back of a traditional tower, they are extremely vulnerable to damage, whether from vehicles or equipment running into them or from the tower itself being accidentally backed into an obstruction while being towed. Factoring in the parts and labor costs to have repairs completed, it could potentially cost a light tower owner hundreds of dollars each time an accident occurs. But with the fixture in an upright, vertical position, the chances of unnecessary damage, downtime and resulting expenses are greatly reduced.

The upright tower mast also improves jobsite efficiency. On traditional towers an operator must position the light fixtures while the light mast is still lying horizontally. Often an operator cannot correctly determine how the fixtures should be adjusted until the tower is in the vertical position. If not correct, the tower must come back down, and the trial-and-error process continues. Because the vertical telescoping tower of a compact unit is always upright, it allows the fixtures to be adjusted and aimed so that a worker can see exactly how they will be aligned when the mast is raised. This design is far more intuitive and makes the task of lamp adjustment simple.

Timing it out

As contractors begin to enjoy the new benefits of enhanced lighting and a more sensible tower design, others continue to reap the rewards of existing light sequence command systems that automatically handle the task of turning lights on and off. Several companies offer such a feature, which can be controlled in various ways depending on the manufacturer.

One method of automatic sequencing utilizes a photocell that detects ambient light. As daylight fades, the light tower’s engine will start up, come to temperature and then turn the lights on. When the sun comes up in the morning, it will turn the lights off first and then shut the engine off. For instances where light is not needed for the entire night, another option is a digital timer that can program the tower to go on and off at specific intervals.

Such a feature could understandably be viewed as overkill for a jobsite with one light tower and six workers who could easily turn it on and off as needed. But in certain applications it can be very beneficial by eliminating several trips a day to multiple light towers in difficult-to-reach locations.

Coal mines will typically position light towers along a haul road or on a high wall, but these areas can be difficult to access. Some construction sites may have dozens of towers, and it could be inconvenient and expensive to stop work in the early evening or morning to attend to them. Towers also may be used for security purposes in locations where people simply are not present.

Often in cases such as these, operators choose to eliminate the headache of running around to turn light towers on and off by leaving the units running at all hours of the day. Or in other instances workers simply may not realize that towers are still on as they work during the day. Either way, more fuel will be unnecessarily consumed, and the potential for equipment wear and tear will grow as the light tower’s engine is needlessly overworked. With automatic light-sequencing capabilities, the chore of manually monitoring these towers is avoided, and workers can focus on more productive tasks.

Built to suit

While automatic light sequencing is a big convenience in the right situations, there are plenty of other applications that can benefit from more substantial light-tower modifications that make the unit uniquely suited to operate more effectively in a given environment. Some manufacturers cater to this by offering custom light-tower packages.

One such package may feature a larger generator offering more kilowatts to provide added auxiliary power for other operations on a site. Cold-weather packages can incorporate a number of added features, from engine cold-start aids and battery blankets to tubes in the tires. Since it could be detrimental to the equipment for snow to enter, these packages also may have a full floor and snow shields around the radiator. The shield still allows for appropriate cooling while preventing snow from entering the cabinet.

With environmental concerns being more of a priority than ever before, manufacturers also are building towers with a fluid containment system as standard equipment. Given that some applications actually mandate that any equipment in use on a site must have the ability to contain all fuel, oil or other hazardous fluid spills, it only makes sense for light towers to be built with those issues in mind.

Don’t make light of value

While any number of factors can differentiate one job from the next, the common denominator among all environments, applications and sites where nighttime work takes place is the darkness that prevails when there is no light source present. But far too often this situation is addressed with a bare-bones lighting solution that is judged by a price tag rather than the overall value it can or cannot provide.

The right light tower can be invaluable. Its design can lead to cost and space savings while preventing damage. Its added features can improve equipment effectiveness and longevity in demanding environments. And its enhanced light output can make workers more productive and jobsites much safer. These are benefits that anyone can clearly see the value in—even without any light at all.

About the Author

Dahlgren is a product manager with Allmand Bros. Inc.

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