In the 1950s when the first hydraulic excavators were introduced, the machines were all equipped with rubber-tire undercarriages. Such configurations continue to be highly popular in Europe today.
In North America, however, wheel excavators have yet to achieve firm footing. "They are still considered a niche product," says Bill Metzgar, product training coordinator, Doosan Infracore America. Popular among county and state governments, these machines are just starting to see more use in road work and scrap handling operations, he adds.
Chad Cremeens, wheel excavator marketing for NACD and LACD, Caterpillar Inc., agrees that wheel excavators are still largely viewed as niche machines. "But for many, it's a niche machine they cannot live without," he says. "For years, the wheel excavator has been an essential part of governmental fleets (municipalities, highway departments, etc.). Recently, private contractors have started to realize the value, as well."
Archer Western Contractors, a division of The Walsh Group, is one such company. This general contracting, construction management and design-build firm handles building, civil and transportation projects throughout the country.
Its Phoenix Regional Office is nearing completion of one the segments of the Valley Metro Rail Line, a light rail system that will run through the heart of downtown Phoenix. Four wheel excavators - two Caterpillar M318s and two M322s - have been on the job almost since its inception roughly 26 months ago. Mobility is the primary reason they were brought in.
"We have nine miles of work through city streets and we have to be able to be a little like 'nomads' - go to work someplace for a few days, pick up and run down the street four blocks, work for a couple of days, then pick up and run down the street to another location," says Bob Fouty, senior project manager.
Being able to make those moves without bringing in transport vehicles is a huge benefit. "We can just basically run them through the streets," says Fouty of the wheel excavators. "It was really site logistics and the need to be completely mobile at a moment's notice."
As part of the project, Archer Western will have performed a complete reconstruction of all the utilities that will pass underneath the future rail line. "We had about 75,000 lineal ft. of storm, sanitary and water mains to replace as part of this construction," says Fouty. "And of course, those are all made up of runs that are 40, 50 or 60 ft. long. It's not one big, continuous pipe."
The rubber-tire excavators proved invaluable for this task. "We used them on all the utility relocation. That was kind of their duties," says Fouty. They were also busy tearing up pavement, sidewalks and curb and gutter, as well as moving Jersey barriers around the site. "For what we used them for, they were workhorses for us for two years."
Their mobility proved crucial to staying on schedule. "Here's an example of a situation we encountered over and over," Fouty cites. "We would be installing a utility - maybe it's a 12-in. water line that crossed Washington [Street]. During the course of the work, we would find an unknown utility. That work stops. You have to either backfill the ditch or shore it, cover it with plates, then be able to pick up and move up the street maybe a block and a half.
"It just became readily apparent we needed that instant mobility, and the ability to make that move without having to arrange a lowbed truck to put a crawler on," Fouty says.
Ease on down the road
Ease of movement around and to jobsites is one reason wheel excavators are such an integral part of the equipment fleet at K-Five Construction, Lemont, IL. This heavy highway construction contractor handles 135+ jobs each year, ranging from large parking lots to interstate highways and airport runways, in and around the Chicago area.