For decades, equipment operators took their instructions from stakes in the ground that had to be moved and reset as the work unfolded. Grade stakes will soon be obsolete, thanks to 35 Global Positioning Satellites that send radio signals to earth. Onboard GPS receivers allow scrapers, dozers, and graders to plot accurate courses with little or no reference to in-ground markers.

Kerr Contractors, Inc. adopted GPS in 2002 when Trimble Navigation introduced the dual-antenna Site Vision system that employs guidance and machine control. Light bars mounted in the operator’s field of vision signal proper blade angle as the machine moves, while a video display shows the proper cut or fill on the job site. The immediate benefits are speed and extreme accuracy.

With GPS, supervisors no longer have to reset stakes, so they can concentrate on haul routes and cycle times. At day’s end they drive their sites in GPS-equipped pickups and send progress data to the home office so estimators can check productivity against the original schedule. All earthmoving tasks and management functions are improved by GPS.

Global Positioning Systems