Reaching for the Sky
Published in: Construction Equipment
Date: 4/1/2001
By: HINDMAN, WILLIAM
Aerial-work platforms have become a common sight on construction projects everywhere, and they are the most commonly rented piece of equipment on almost every job
Reach for the sky” may sound like dialogue from an old western movie, but it’s really what’s happening today on construction sites everywhere. Aerial-work platforms, with higher working heights and greater horizontal-reach capabilities, have become a common tool on the jobsite and are being used for a wider variety of applications than ever before.
Currently, there are a number of construction projects throughout North America including stadiums, convention centers, steel mills and large manufacturing facilities where these high reach aerial-work platforms are being used for everything from steel erection to the installation of window glass and trim.
A few years ago, the maximum platform height that most manufacturers of self-propelled boom lifts offered was in the 60- to 80-foot range. They were, and still are, the mainstay of the industry. But today, boom lifts are available with platform heights of 100, 120 and even 150 feet. Not only are they taller, they are more versatile, with increased work envelopes and greater platform capacities on some models.
One of the biggest advantages of these higher-reaching machines, however, is their horizontal outreach capability that allows them to reach over ground-level obstacles like jobsite debris or soft, muddy or uneven terrain and still reach overhead areas. Unlike smaller lifts, these larger machines don’t have to be placed directly under the overhead area where work is to be performed; they can be positioned close to the work area and can extend up and out to reach places that are inaccessible by almost any other means.
There are two types of high-reach boom lifts–telescoping booms and articulating or knuckle booms. Telescoping boom lifts extend out in a straight-line direction only, which can limit overhead accessibility in some situations. Some telescopic models are equipped with a jib boom on the end that allows for some limited “up-and-over” movement in the air. These jib booms are usually only about 6 feet in length, however, so they are used mostly for precise positioning of the platform at the overhead work area.
Articulating boom lifts, on the other hand, are more versatile and can be elevated almost straight up above the base from a stowed position and then extended out to the work area (see illustration, pg. 28). This allows them to reach over structures or obstacles that might restrict access to an overhead area if a telescoping boom lift were used. Another feature of articulating boom lifts that makes them more versatile on the job is that, due to the articulated configuration of the boom, they can be elevated more easily in tight or confined areas.
The largest self-propelled aerial-work platform on the market today is an articulating boom lift–the JLG Model 150 HAX. It features 150 feet of platform height, up to 1,000 pounds platform capacity and a maximum horizontal outreach of almost 80 feet. Although some telescoping booms may offer similar outreach distance capabilities, they do not have “up-and-over” capabilities that allow the boom to maneuver around obstacles above the ground.
Most high-reach telescoping booms with working heights over 100 feet have horizontal-reach capabilities between 60 and 70 feet, but because of the telescoping action of the boom, they are only able to extend in a straight direction. The Model 150 HAX, because it is an articulating boom, can reach up, out, over and down around obstacles. It offers 79 feet 3 inches of horizontal reach at 42 feet 7 inches above ground level, has 72 feet 4 inches of outreach at 80 feet above ground level, and still provides almost 60 feet of horizontal reach at 120 feet above the ground. An additional advantage of the 150 HAX’s articulating boom design is that it can also reach more than 30 feet below ground level, making it a versatile machine for a wider variety of applications including work on bridges, pilings, foundations and other types of jobs that require below-grade access.
Recently, Glenco Construction Services of Lewistown, Pa., rented a Model 150 HAX articulating boom lift from United Rentals and a number of JLG 120 HX telescoping boom lifts from Best Line Equipment to help erect the steel structure on the Beaver Stadium expansion and renovation project at Penn State University in State College, Pa. The 150 HAX was needed for the project because it was the only practical way to reach the upper concourse and club-level truss connections on the South addition and inaccessible welded connections on the East suite addition. It also allowed Glenco to perform concurrent tasks on the job.
When the massive steel structure was being erected using the high-reach boom lifts, smaller articulating boom lifts were being used to do some of the other work. Because of the horizontal-outreach capability of the 150 HAX unit, it could be positioned away from the structure so that the smaller lifts could work in close proximity to it without interference, while still providing enough working height capability to reach the overhead areas. In the areas where the 120 HX telescoping booms were being used, they had to be positioned closer to the structure, so the smaller units were not able to operate at the same time in the same area.
With the booms working together, Glenco was able to maintain tighter control of construction schedules by maximizing the amount of work that could be performed simultaneously. In addition, since all of the booms on site could be driven at their full elevation, they could be easily moved around to gain access to other overhead work areas without having to spend valuable time lowering and raising the boom each time they changed position.
In Kentucky, an even larger project involving the use of high-reach booms is taking place. Horta Construccions Metalicas, a specialty contractor from Spain, is doing the steel erection on a huge melt shop addition to the North American Stainless facility in Ghent, Ky. Since the project began almost six months ago, they have utilized two 150 HAX articulating boom lifts and have had up to a dozen 120 HX telescoping boom lifts on the site at the same time. Because of the extremely tall ceiling heights in the huge facility, it was the only way they could reach the areas where they needed to work.
Since they were first introduced, aerial-work platforms of all types have become a common sight on construction projects everywhere. In fact, they are the most commonly rented piece of equipment on almost every job. They can do things and reach areas that are inaccessible by any other means. They help you become more productive and they increase workplace safety.
Although renting for $20,000 or more per month, high-reach aerials are being used for a wider variety of applications than ever before as contractors become more familiar with their availability and versatility. With their enormous amount of horizontal-reach capabilities, high-reach booms are often the only way to safely access overhead areas.
World’s Tallest Aerials
When it comes to reaching record heights, trailer or truck-mounted aerials win hands down. Last year, Bronto Skylift of Tampere, Finalnd, introduced the tallest aerial built to date–the S 288 HLA–with a 288-foot maximum platform height.
Although there aren’t any of these huge machines in North America at this time, there are other Bronto Skylifts–including an S 236 HLA with 236 feet of platform height–that are available. The S 236 HLA is the tallest aerial in North America, and it’s available for rent from United Rentals. In addition to its height capabilities, the S 236 HLA offers 90 feet of horizontal reach, 130 feet of working height and an unrestricted platform capacity of 1000 pounds.
Renting for about $48,000 per month, the Bronto S 236 HLA is often the only practical solution to reaching overhead areas. Recently, LBL Sky Systems of Quebec, Canada, contacted United Rentals about a problem they had. LBL was contracted to replace window glass on a tall dormitory/classroom building at Baruch College near Lexington Avenue and 25th Street in New York City. Their problem was that the front of the building was convex and they couldn’t use scaffolding to reach the windows, and other aerials just weren’t tall enough. The solution to their problem was the Bronto S 236 HLA.
Although truck- or trailer-mounted aerials can’t be driven around a worksite like an articulating boom lift, they do have the advantage of being able to be moved quickly from one job location to another. They don’t have to be loaded and unloaded onto a truck. You just stow the booms, retract the outriggers and drive away. Available in a variety of working heights, they can be the ideal aerial-work platforms to use when they are going to be moved around to a number of different locations, or you just need the extra height, greater horizontal reach or larger platform capacity.
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