A Flexible Upgrade

Machine grading control systems have something in common with project delivery systems
By Don Talend, Contributing Editor | October 2009 Vol. 64 No. 10
A Haydon operator views a topographical layout of the AZ job site on a GX 60 monitor while digging with a Caterpillar 330 CL.

The most commonly cited benefits of Global Navigation Satellite System (GNSS)-enabled machine control are grading and excavation productivity, and the cost savings that result from a reduction in manual tasks such as excavation depth verification using conventional surveying methods. The use of this technology on recent underground utility work for a state vehicle maintenance facility outside of Phoenix demonstrates that it has something in common with the Construction Management at Risk (CM at Risk) project delivery method, in which cost control is a major priority.

In early 2009, Haydon Building Corp., Phoenix, constructed a 24,000 square foot, $9.9 million field maintenance shop for the Arizona Department of Emergency and Military Affairs (DEMA) in Florence, AZ, located about 60 miles southeast of Phoenix. It was one of the first projects in which Haydon used GNSS to control an excavator digging for underground potable water pipe, sewer force main, gravity sewer and storm drain pipe servicing the new facility, which is equipped with work bays and a lube bay for DEMA vehicles, as well as administrative areas. All told, Haydon installed 3,535 feet of 10 inch PVC pipe for potable water, 2,000 feet of 4 inch high density polyethylene (HDPE) sewer force main, 500 feet of 8 inch PVC gravity sewer and 100 feet of 12 inch HDPE storm drain. All but the potable pipe was new and not tied into an existing system.

Under the CM at Risk method, the construction manager serves as part of a team with the owner for the design and construction phases of a project. During the construction phase, the construction manager’s role converts to the legal equivalent of a general contractor once a guaranteed maximum price is established for the construction work. The construction manager is responsible for ensuring that the project stays on schedule and conforms to the contract details and, therefore, takes on more of the risk that other project stakeholders otherwise would assume. Benefits of this approach include flexibility, quality control and cost control; rather than managing multiple contracts, the construction manager can bid and subcontract a portion of the work at any time and sign the construction contracts, even when the design of an unrelated portion is not complete.