Some contractors shine at night, while others may prefer the day shift. For obvious reasons, working the night shift poses unique challenges not faced under the sun. For one Denver-based contractor, night work raises the bar, separating the men from the boys. In a recent case study from Komatsu America, that contractor claims that it excels in the “out-of-the-ordinary jobs…those that are on the fast track, or involve night work or any other element that may make it uncomfortable for other contractors.” The contractor goes on to say that “a preference for the more difficult jobs tends to eliminate the marginally qualified contractors and leaves the rest of us on a level playing field where we all understand the job, understand our costs, and understand the need to make a profit.”
Whether a project is on a fast track or not, more and more construction work is being done at night. Simply put, counties and states do not want to disrupt heavy daytime traffic flow. According to the Texas Transportation Institute, up to a third of roadwork is done at night in many states, and in several states it’s up to a half. With that said, it’s clear that those who avoid the night shift may be leaving a lot of dollars on the table.
“Planning for effective night work is a key element. The lighting plan, particularly, needs to be
written, verified, and tested to make sure that lights and towers will provide adequate lighting and will not blind either the workers or the public,” says Julie Carter, environmental health and safety manager for Traylor Brothers, Inc., which is headquartered in Evansville, IN. Carter adds that contractors should almost overplan for night work and always have a backup in place for all required equipment. “You can’t have enough reflective material on your workers and on your equipment. Shadows can be misleading and can be mistaken for other things. So knowing your surroundings and planning during the day—to work at night—is essential,” she says.
Behind the Lighting Guidelines
After researching a number of the reports available online, one discovers that there is nothing simplistic about developing a lighting design. According to the National Cooperative Highway Research Program (NCHRP), anyone responsible for a light plan should be knowledgeable in photometrics (measurements of the properties of light, especially luminous intensity) and should consult the NCHRP reports from which numerous guidelines have been developed.
The NCHRP reports have served as models for state DOTs in developing standards for safe night work zones and proper lighting design. In fact, for contractors and DOT staff, the American Traffic Safety Services (ATSSA) offers a training course that is based heavily on NCHRP Report 476 and later efforts. One of the goals of the ATSSA is to standardize night work zone designs across the nation, as currently there are a limited number of existing standards and regulations for lighting nighttime construction operations. Many states leave lighting decisions up to the contractor—and since proper work zone lighting affects construction workers and the general public, lighting design should require the most effective approach possible.
For example, the New York State DOT (NYSDOT) issued requirements for nighttime construction as early as 1995, providing recommendations for the lighting plan, inspection procedures, illuminance levels, lighting equipment, and glare control. Such states as Illinois, Michigan, North Carolina, New Jersey, and Maryland have drafted varying specifications as well.
In the Dark
Why are lighting design guidelines difficult to implement? The Texas Transportation Institute conducted extensive research in the field and uncovered various obstacles. Indeed, since lighting design is typically left to the contractor’s discretion, lighting is often insufficient and improperly oriented. A 2007 report states that up to 30% of the contractors studied did not know the types of lamps they use for their operations. Forty-two percent of those surveyed use three or four lighting towers regardless of the work being performed.
For mobile operations (such as milling and paving), according to the study, the continuous
movement of the operation made it difficult to maintain the uniformity of light. In many cases, the direction of lighting caused severe glare to motorists and resulted in disabling shadow zones. While the effect of glare on motorists was ultimately addressed, often overlooked were similar glare concerns for workers on the site.
Finally, the study stresses that only a small portion of resident engineers or contractors actually use any type of light-measuring equipment to evaluate or verify lighting adequacy, glare, or light pollution.
Illumination 101
Sales engineer Doug Dahlgren of Allmand Bros. Inc., a manufacturer of a wide variety of portable light towers, outlines the basics in his recent safety article. He steers contractors to information provided by the Illuminating Engineering Society (IES), a group of lighting industry experts, who have established guidelines determining how many foot-candles of light a particular job site requires. A foot-candle is the intensity of light per square foot of surface area. By calculating the size of the area to be lit, the correct amount of light needed can be determined. Other factors include the type of project and the existing weather conditions. For example, more light towers may be needed on black soils or asphalt, as each absorbs more light; and if skies are cloudy, additional illumination may be required.
Dahlgren says that after establishing the correct level of lighting, one should consider the location and positioning of the light tower. Seek a surface that is flat and firm, as a portable light tower could potentially fall over if placed on rocky or sandy soil, or on an uneven grade; and beware of overhead obstructions such as power lines or trees.
Next, the correct positioning of the tower’s fixtures creates optimum visibility for workers on the job site, but is not blinding to oncoming traffic. “Some newer light tower designs, such as vertical-only towers, allow all light fixtures to be directed straight down if needed, which can significantly reduce potential distraction to motorists,” says Dahlgren. He adds that tilting the fixtures down 20 degrees increases the efficiency of the light tower by focusing the light on the job site and minimizing the amount reflected skyward. Another important technique, he says, is placing the light towers on each side of the job site so that they face each other. This helps reduce shadows and eliminate dark areas to increase construction site visibility for workers.
It’s important to note that the above report stresses that equipment-mounted lighting systems may also be advantageous to increase lighting from one level to the next. For example, portable lights may be placed immediately in front of and behind a paver; or a supplemental luminaire may be mounted on a vehicle and moved from joint to joint in pavement repair operations to increase illumination from Level II to Level III.
Equipment-mounted lighting strategies, says the report, offer a number of advantages when compared with area floodlighting. They include, among others, an opportunity for the operator to adjust light to direct high-intensity illumination where needed. The equipment can also be operated independent of general illumination; and the need for such equipment as floodlighting trailers and generators is minimized, which eliminates time and labor spent in transporting and erecting such equipment.
Balloon Lights Versus Portable Light Towers
Entering the North American construction market over the last five years, balloon lights are portable, lightweight, self-inflating units that are able to operate off of a portable generator or any 20-amp circuit. Versus portable light towers, their advantage is glare-free lighting, as the light is diffused via a balloon-like covering. Some lighting equipment manufacturers offer both balloon lights and portable light towers. Others offer only one or the other. As such, comparisons between the two are often made; and the advantages and disadvantages of each are often discussed. In short, aside from the issue of glare, balloon lights are touted as more portable, and more quiet. Alternatively, traditional light towers are said to give a wider area of light coverage and can be tilted to illuminate other areas. Both types have their markets and applications.
A report presented at the 2010 Transportation Research Board Annual Meeting studied the glare and light characteristics of conventional (light towers) and balloon lighting systems. The abstract of the report states that “the results of this study indicated that while being comparable in terms of wattage and luminous flux, the tested balloon light systems differed in terms of light and glare characteristics. In addition, while the conventional light tower provided greater intensity of illumination at the light source than balloon lights, the disability glare was greater for the conventional light tower than balloon lights mounted at the same height.” Note that contractors should be encouraged to examine the study in its entirety to ascertain what equipment or combination of equipment is best for a particular application. The report can be ordered at pubsindex.trb.org.
John Wessels, national sales manager-construction/rescue, for Airstar Space Lighting says that his company is literally the inventor of lighting balloon technology. “This unique concept was introduced to the film industry in 1992, offering helium-filled balloons to replace traditional film lights, saving time and money. Airstar’s efforts paid off, earning numerous awards, including an Academy Award for Technical Lighting Achievement in 1993. In 1996, the company entered the construction industry with its Sirocco line of lights,” says Wessels.
The Sirocco lighting systems quickly became the standard in the construction industry for safety lighting, says Wessels. “Throughout the next 13 years the company worked closely with state DOT’s and government agencies to help set guidelines in the industry to make construction zones safer for workers and drivers. Currently, a dozen states have developed new standards for lighting flaggers and work zones. Many more states recognized the value of this technology and are currently using Airstar lights for their own operations,” he says.
The Sirocco line offers portable, glare-free systems producing higher efficiency and a greater visibility than traditional construction lights, says the company. These units provide 360-degree illumination without hot points. Because of this unique technology, a person can look directly at the balloon without strain on the eyes. The specialty envelope diffuses the light evenly, producing a daylight effect.
Airstar Space Lighting manufactures a large selection of balloon lights, with 12 different lights available ranging in size from 12 V up to the most powerful light, a 4,000-watt HMI.
Ingmar Hansen is vice president of Powermoon Enterprises Ltd., which offers a wide variety of lighting balloon products with a patented “open-close” technology. “Powermoon lights open and close with a patented steel-spring mechanism that does not depend upon air pressure to operate. This prevents the balloon from accidentally deflating,” says Hansen. Made of tough materials such as steel, aluminum, or Kevlar, this mechanical system makes the Powermoon light a unit which can be used either installed on long-term construction sites or as a portable unit mounted on machinery, he says.
Powermoon offers a complete line of models with different lighting technologies, lighting outputs, and user features. Most common are units with 2,000-watt halogen, or 1,000-watt, or 2,000-watt Metal Halide bulbs. All units come with a shock-absorbing bulb-mount system for machinery mount and take all U.S. bulbs. “A Powermoon Profil 1,000-watt metal halide unit lights up an area of about 30,000 square feet glare-free and like daylight,” says Hansen.
Ingersoll Rand offers the BL2000, which, according to the company, typically takes about five minutes to unpack, inflate, and mount. Once removed from its storage case, it plugs into a 120-V/20-amp outlet, and an internal fan inflates the shroud. Tiny vent holes provide circulation for cooling and prevent over-inflation. Mounted onto optional stands or fixed directly on any piece of equipment, it inflates in less than a minute and provides instant illumination, diffusing glare-free light over a 360-degree area. Weighing less than 40 pounds, it packs into a container small enough to keep in a car.
The Wacker Neuson lighting product line now includes the LB 1 Light Balloon. This light balloon quickly and easily brings glare-free light to the construction site so crews can keep working in evening, night, and low-light conditions, says the company. This portable lighting solution offers a 1,000-watt metal halide balloon light, tripod, and 120-V portable ballast. The upper portion of the balloon is a reflective-aluminum-coated, durable Kevlar fabric that reflects the light down, maximizing lumen output at ground level.
Wacker Neuson says its rugged light balloon tripod system is easy to set up and take down and offers two anchoring options for added stability; carabiners for tie-down and staking through the bottom of the legs. The three-piece stainless steel tripod is height adjustable up to 13.5 feet and is intended for outdoor use.
The LB 1 portable lighting package weighs 93.6 pounds and provides 99,000 lumens covering more than 35,700 square feet at one foot-candle. A simple, one-step mechanical opening system eliminates noisy fans and holds its shape in windy conditions. The light balloon complements the Wacker Neuson line of equipment that includes a line of light towers and portable and mobile generators.
The Next Level in Portable Light Towers
“Today’s towers are engineered to help eradicate common lighting challenges contractors have faced for decades. For example, light fixtures are now designed to help eliminate ‘hot spots,’ an area that receives a high concentration of light while another location is left in the dark. These fixtures distribute light more evenly to cover a job site more efficiently,” says Dahlgren. “Currently, they also provide more light than ever before. Light towers with 1,250-watt lamps and ballasts are providing 150,000 lumens per lamp, a 36% increase over the 110,000-lumen output of the longtime industry standard of 1,000-watt lamps,” he adds.
Dahlgren also says that the popularity of a vertical-only tower design is also growing steadily, as safety and ease of use become essential when choosing portable lighting. “New vertical-only towers are safer to operate and tow than traditional lay-down towers since there is no overhang over the back of the trailer and the operator is positioned away from potential danger as the lights are being raised or lowered,” he says.
Other job-site safety and security features include automatic lighting sequence and command control systems. “These systems automatically turn lights on and off at a set time, eliminating manual operation. Photocell sensors start the unit’s power at dusk and shut down the tower when the sun rises. This removes the need for a person to take time away from a job to turn the light tower on and off while lowering the risk of accidents caused by operators crossing busy construction areas,” says Dahlgren.
Easier transport from job to job is another factor. “Today’s light towers are created with portability in mind, yet they are designed to withstand the rigors of travel. Instead of modifying permanent stadium or parking lot lighting, portable towers offer the durability necessary to stand up to the demands of a job site. These advances in technology and design have not only made portable light tower usage safer, but have also created better lighting for work environments,” says Dahlgren.
Allmand Bros. has now added the V Series vertical light tower configuration as an option for certain Maxi-Lite Series light towers. With standard light towers, when the light mast is retracted, it must be folded down across the light tower for storage, transport, and light fixture adjustment. But with the V Series design, the mast retracts and telescopes straight up and down in its own vertical housing, which results in much easier setup, simplified shipping, towing, storage, and reduced potential for damaging the lamps.
By utilizing Allmand’s proprietary engineered SHO-HD 1,250-watt lighting system, the Maxi-Lite Series provides 150,000 lumens per lamp, a 36% increase over some competitive light towers, says the company.
Wacker Neuson offers a new series of portable light towers. According to the company, the new LTN 6 (light tower narrow body, 6-kW generator) with its compact design takes up less room on the job site and/or in the rental yard, plus reduces freight costs by allowing 11 units to be transported on a truckload.
“The housing has been changed from the box metal style to a unique, streamlined, curve design made from a high-impact plastic. This material is incredibly durable. It’s virtually dent- and rustproof, which extends the life of the unit, especially in the harsh elements,” says Marc Leupi, utility product manager for Wacker Neuson.
Borrowing from the automotive industry, the LTN 6 is the first light tower to utilize a stamped 10-guage steel tub, which provides superior strength and full protection from ground debris. “The fully enclosed bottom is also key to reducing sound emissions,” says Leupi. “The LTN 6 sound level is as low as 67 dBA at 23 feet which is an impressive number when you consider the industry average is over 70 dBA.” This steel tub and all of the other metal surfaces, including the inner mast sections and outriggers, are protected by durable powder-coat paint, and all external hardware is zinc dichromate treated for extreme rust resistance.
Beyond the Light While lighting design is a key factor, safe nighttime work zones require so much more. An easy way to train and test your nighttime safety knowledge, is by visiting the Caterpillar Safety site at safety.cat.com, which offers videos on overall night work safety and fatigue avoidance, as well as hundreds of other topics. As these videos stress, visibility is not only affected by darkness but also by dust, rain, or snow. So, when you’re heading off to work tonight, see and be seen—and leave the night lights on.The sharp rise in night work, particularly as contracted with Departments of Transportation, is not only driving utilization of light towers and other categories of equipment, it is also driving R&D. Manufacturers have two specific concerns of night work on their radar—noise and vibration—and rental companies need to be part of the solution.California is just one example of a state where almost all DOT contracts in urban areas are now awarded as night work. This adds to rental demand, as does the economic need for contractors to work longer days and “shoulder seasons” to make ends meet. The nature of night work means that safety and efficiency must dovetail with environmental issues—requirements that usually mandate newer equipment technologies.Clay Johnson, strategic sourcing manager for United Rentals, says the company has steadily increased its overall fleet of light towers since 2006. Availability has been enhanced by a net increase of over 1,300 units in the past two years alone. “And that’s in an economic downturn,” Johnson notes.
“In order to be considered a reliable player in lighting rental, you need to have ample product available. Contractors who request towers for night work almost always rent multiple quantities, so depth of fleet is important.”
United Rentals has responded to the growing climate for environmentally friendly equipment by offering solar light towers as an option to traditional diesel units. The company will retail the equipment, and plans to test potential rental applications in areas damaged by natural disasters where conditions make fuel scarce and transport difficult. “The towers are completely powered by renewable solar energy, so they offer the triple benefit of being free to operate and completely quiet, with zero carbon emissions,” notes Johnson.
Hydraulic Operation
The AL8000 HT from Genie features an articulated mast with smooth, convenient hydraulic operation. The mast extends up 28 feet and out 20. And with a noncontinuous boom rotation of 359-degrees, operators will be able to find the precise operating position for their job sites. The hydraulic tower allows for fast setup, which can increase productivity.
Rotating Bars, Pivoting Lights
The tower’s light bar section tilts 180 degrees, and each light pivots in two perpendicular directions—front-to-back and 360 degrees side-to-side. Each bulb can be pointed in a different direction to meet the lighting requirements for various work areas, especially those that demand an exceptional range of movement to light around obstacles. A simple spring clip locks each light in place for steady, consistent illumination.
Powered by a 13.6-horsepower Kubota engine, the AL8000 HT comes standard with four 1,000-watt bulbs. Eight lights are optional and will give the operator maximum light coverage for hard-to-light work sites.