You dig, right? What government fleet doesn't?
Many public works departments use a backhoe for everyday jobs, resorting to an excavator for special occasions.
Excavators are more versatile and perform better now than excavators of a decade and more ago, according to manufacturers. While this is good news, it means purchasers and renters should do more research on the equipment to ensure they make appropriate purchasing and spec'ing choices. The user has a range of factors to consider, including size, weight, reach, tail swing, horsepower, attachments, auxiliary hydraulics, and breakout force.
Whether a fleet rents or purchases an excavator, it still must ensure the machine's specs match up to the work required.
Rent or Buy?
Fleets have various ways of determining when to rent or buy an excavator, with many finding rental sufficient for their needs.
"When the reach and depth requirements exceed those of a backhoe, organizations will often rent an excavator, but relatively few municipal fleets actually buy one," said Chris Amos, CAFM, commissioner of Equipment Services for the City of St. Louis.
Walter Burnett, CAFM, public works director for the City of Macomb, Ill., said, "We occasionally rent an excavator when the project warrants it. Our decision on size is almost always based on when the excavator will do the job better than one of our backhoes. Often, we rent a mini excavator if the workspace is tight and sometimes larger machines are needed when the job requires greater digging depth or breakout forces than our backhoes can provide. Our most recent rental was for a 48-inch reinforced concrete culvert project across a street. In that case, the weight of the pipe sections was the determining factor."
Stephen Kibler, ACFM, fleet manager for the City of Loveland, Colo., offered a rule of thumb for fleet managers: If excavator utilization is less than 400 hours per year, rent it.
"Our standard workload does not currently justify our purchasing an excavator," Kibler said. "Most underground main leaks in Loveland involve a six-inch or smaller pipe. Access or excavation is accomplished by a backhoe 95 percent of the time. If a larger main needs accessing, a contractor would be hired to do the excavating."
Kibler added, "mid-sized, rubber-tracked units that are more maneuverable seem to be the best value in a municipal environment. Most excavating needs are predominately in the roadway, and pavement damage needs to be minimized."
Managing Specific Demands
Transporting an excavator to a jobsite is also an issue, in part because side streets aren't always large enough to allow off-loading. In Loveland, Kibler said the Water Department will drive a backhoe as far as 10 miles to a worksite, which accounts for 50 percent of the equipment wear-and-tear. (The size and weight of the machine also determine the size of a trailer and towing vehicle, and whether the driver will need a commercial driver license.)
Government fleets deal with different demands day-to-day, often shaped to some degree by geography and seasonal weather patterns, among other factors.
Flooding and mud slides come with the territory in Snohomish County, Wash. Excavators are used to move rock and riprap into place for flood control and to clear mud slides.
The Snohomish County Department of Public Works (DPW) has 11 excavators: five crawler excavators, four mini-excavators, and two wheeled machines. They are from a mix of manufacturers, including Caterpillar, JCB, John Deere, and Komatsu, said Allen Mitchell, CPFP, fleet manager for Snohomish County DPW.
"We rent additional machines if we're busy," Mitchell said. During the construction season, the road division, which has 170 employees, hires half as many again for summer help. Seasonal employees are limited to operating pickup trucks while the full-time, experienced employees are assigned to the excavators and other more sophisticated equipment, Mitchell said.
Spec'ing the excavators for various uses requires consideration of a wide range of factors that include boom reach, maximum loading height, and swing radius.
An excavator spec'd with hydraulics to run a well-chosen variety of attachments is a very versatile machine, Mitchell said. Snohomish County's excavators are used for solid waste management, parks maintenance and construction, and road repair and construction.
At transfer stations, the County uses excavators with a hydraulic thumb attachment to sort and pack recyclables. In the County's parks, an excavator with a mower attachment replaced a traditional mower, and an excavator with a hydraulic thumb attachment is also used for parks projects such as reconfiguring drainage systems. The road crews use excavators with pavement breakers; they also use a hydraulic thumb attachment to load catch basins and culverts on and off trailers and to plant trees. Road crews use the mower attachment for drainage projects along rights-of-way and to remove debris from bridge structures to prevent flood damage.
For construction projects, a compactor attachment comes in handy for compacting soil to minimize settling once a concrete slab is poured. To dig for construction projects, the County usually specs two or three buckets of varying widths, Mitchell added.
A compact or mini excavator can cost about $95,000 and a large excavator around $350,000, Mitchell said. As for service life, Mitchell said, "We don't go beyond 10,000 hours. After that, there can be major rebuild costs." That number of hours usually translates to about 15 years, Mitchell said.[PAGEBREAK]
Spec'ing the Right Excavator
Tom Connor, Bobcat's excavator product specialist, pointed out a fundamental question anyone purchasing or renting an excavator must ask: Can it lift what needs to be lifted? Manhole covers, Jersey barriers, and large trees are typical items that might have to be handled.
Beyond that, auxiliary hydraulics to run attachments are crucial, Connor and other manufacturers agreed. Purchasers typically order three to five attachments, Connor said. Besides a couple of buckets of different sizes, a hydraulic thumb is widely valued for the versatility it provides. Another important attachment is a breaker or "hammer" to break through pavement.
For the sake of ROI, "you want to use an excavator all day," said Keith Rohrbacker, product manager of Kubota, and attachments can help make that possible.
Systems or designs that support attachment changes yield multiple benefits, notably time savings. Some manufacturers offer a quick-exchange system. Besides enhancing productivity, these also can provide a safety advantage, Rohrbacker said, considering attachments can weigh hundreds to more than 1,000 lbs.
Apart from ever-present budget considerations, the type of work or range of projects largely determines the size and weight of the excavator that can be used. In this context, tail swing must be taken into account. Reduced tail swing allows a machine to get closer to an obstacle or function in a restricted space, said Mark Wall, product marketing manager for John Deere Construction & Forestry Co.
When spec'ing, always account for tail swing. Bobcat's Connor recalled a recent visit to St. Louis, where the sewer department was considering what sort of machine it would need for residential repairs that would require digging six to eight feet in backyards, where maneuverability would be at premium. Some excavators can narrow their track base to pass through smaller areas, for example.
Amenities such as a cab enclosure with air conditioning and heat were unheard of a decade or more ago. While these provide operator comfort and can support productivity, some crew chiefs might be averse to spec'ing them, Rohrbacker said, because they want the operator to be in constant contact with the ground crew, and they also sometimes want the operator to get out of the cab to help with certain tasks.
Fixating on horsepower when spec'ing an excavator can be a mistake, several manufacturers stressed. The engine drives the hydraulic pumps and "that's all it does," Rohrbacker said. "An excavator can have less horsepower than another machine and perform better because of its hydraulic system."
Compact Versus Full-Size
A number of fleet managers said they tend to use compact or mini excavators.
When choosing a compact excavator, make sure the piece of equipment will be adequate for 85-90 percent of jobsite needs, said Tom Reith, construction product manager for Terex. "Don't sacrifice power, breakout force, or anything else just to save a dollar," Reith said.
Reith added that a compact excavator must be durable and reliable because downtime is expensive. The undercarriage is the most costly part of an excavator, comprising almost 20 percent of a machine's purchase price and nearly 50 percent of its maintenance cost, according to Terex.
Though some fleet managers might favor compact machines, sometimes more is called for. An advantage of larger, wheeled excavators, for example, is that they can be driven along roads at, for example, 17 mph, to a water main break, fitted with a hammer attachment to break through pavement and a bucket for digging, refill the opening once repairs are made, and be driven away.
Unlike years ago, the range and choice of excavators has grown now to the point that a user can seek out a "best fit" rather than take a one-size-fits-all approach, pointed out Jason Walker, governmental support consultant with Caterpillar.
Agencies should consider spec'ing additional hydraulic capabilities from the factory, he added. This not only provides increased versatility but can also significantly reduce the cost of these options compared to having the modifications done in the field after the fact.
Training is another important element Brian Stellbrink, Americas excavator product specialist for Caterpillar, noted. Most manufacturers provide some level of training upon delivery of the machine, but this usually just covers the basic walk-around. Given the complexity of these machines and the technology involved, Stellbrink said, customers should include specific training provisions in their requests both for operators as well as technicians.
In addition, most manufactures provide details about their machines online.
Meanwhile, the excavator market is always changing, with frequent new developments. Last year, Komatsu introduced a compact hydraulic excavator designed for construction, utility, landscaping, and other small- to mid-sized applications. The machine is equipped with wireless technology that sends operating information to a secure website. Operating hours, machine location, maintenance notifications, out-of-area notifications, machine utilization, and residual fuel levels are relayed to the Web application for analysis.
- Chris Amos, CAFM, commissioner of Equipment Services, City ofSt. Louis. E-mail: email@example.com
- Walter Burnett, CAFM, public works director, City of Macomb, Ill.E-mail: firstname.lastname@example.org
- Stephen Kibler, ACFM, fleet manager, City of Loveland, Colo.E-mail: email@example.com
- Allen Mitchell, CPFP, fleet manager, Dept. of Public Works, Snohomish County, Wash. E-mail: Allen.Mitchell@co.snohomish.wa.us
- Bobcat. www.bobcat.com
- Caterpillar. www.govbidspec.com
- John Deere. www.deere.com
- Kubota. www.kubota.com
- Terex. www.terex.com