Urbanization has become a significant driver for many equipment design and technology trends in the access industry. With less open space, buildings are becoming taller, and the distance between them is narrower. As buildings go up vertically instead of out horizontally, the demand for higher-working, farther-reaching equipment is on the rise.
Equipment options for work at extreme heights
Historically, cranes were considered the only equipment capable of accessing job sites higher than 100 feet in the air. But, cranes are only designed to lift materials, not people. With buildings and other structures (think bridges, cellular towers, electrical transmission substations, shipyards, stadiums, steel mills, and oil and gas refineries) getting taller, the need to get workers to height has changed what type of equipment can be used to get work done.
Aerial work platforms are the solution when the work requires lifting people in the air. But when the work requires lifting people to extreme heights (defined as greater than 100 feet), only a few types of aerial devices can go that high, including truck-mounted aerials, mast climbers, suspended work platforms, and self-propelled boom lifts.
Let’s take a brief look at each of these options.
Truck-mounted aerial work platforms can rival a crane’s lifting height, today going up to more than 300 feet in platform height, and they have the advantage of being designed to travel on roads so they can get to and from different job sites. The disadvantage is that they need to be driven by a professional driver, and they are rented with the driver/operator, further adding cost to the project. Their on-highway chassis design can make these trucks more diffcult to manoeuvre once on site, especially across unimproved terrain.
Mast climbers are also designed to get workers up to extreme heights, but once installed this type of equipment cannot be moved until the work is done. That really limits its flexibility to be used in different locations across the job site. Another limitation is that a mast climber should be positioned on the ground, and many buildings have lower levels with a larger footprint than the tower. Mast climbers also do not have up-and-over reach capability.
Suspended work platforms are positioned at height by hoists or rigging systems that are either a permanent part of the building, on tracks that travel around the perimeter of the building, or can be temporarily installed. Like mast climbers, this type of equipment cannot quickly or conveniently be used at different locations within the job site. Still, it is most effective when servicing simple vertical surfaces.
Self-propelled boom lifts, like the other equipment options mentioned, are purpose-built for this work. Their advantage is that they are designed to be driven while elevated; in fact, many models offer drive-at-full-lift-height capability so workers can keep going when overhead work requires them to move or reposition. These machines’ compact footprint also allows them to be used in smaller, space-restricted areas.
As equipment design and technologies have advanced, along with innovations in safety features, many boom lift models can achieve great heights. The largest boom lifts on the market today provide the reach needed to put workers up to 19 to 20 stories high, translating to the ability for workers to get projects done 180 to 200 feet above ground level.
These advancements have led to increased demand for taller boom lifts. With that demand comes the need to explain what these machines can do and how they can do it. For example, a few factors need to be considered when making the equipment selection for work at extreme heights: the machine’s chassis design and transportability, as well as its envelope control.
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