With conventional survey methods, the crew generally occupied a location for 10 seconds to obtain a position and then spent countless hours moving from one point to the next and setting up their equipment. Now, they simply mount the receiver in a vehicle and obtain surface topography on the fly while driving as fast as 40 miles per hour. The GPS receiver obtains topography position fixes approximately once per second, or at specified distances, according to the crew's needs. Along with the benefits, working with GPS in the mining environment has presented some challenges. This can cause multipath interference and make it difficult to obtain satellite lock.
Equipment working between a high wall and dragline can also experience problems initializing.
At Black Thunder, the surveyors obtain adequate satellite coverage about 95 percent of the time. As GPS and other technologies, such as laser and radar, continue to advance, so too does the possibility of autonomous mining operations. In time, it will likely be standard in the mining industry. Thunder Basin hopes to remain on the leading edge of this evolution. For its vehicle monitoring and dispatch, the mine is using a Placer 400 GPS receiver, also from Trimble.