Machine Control Fills Needs in Houston Light Rail Project

Network Makes a Difference

In addition to tight access, the project's proximity to downtown Houston presents a number of challenges. When trying to attain, and maintain, a signal, even having two constellations of satellites available can sometimes be no match for a cluster of 60-story buildings.

To address this, the HRT team is utilizing both a number of Topcon total robotic stations and accessing the GeoNet RTK network made available through GeoShack. GeoNet is available to customers in the Dallas/Fort Worth area, Houston, Austin and San Antonio, TX, Cleveland and Columbus, OH, and Toronto, Canada.

"For the HRT crews, the fact that they can have coverage throughout the footprint of the project — and get millimeter accuracy for final grading — is huge in itself," says Scott Bird, GeoShack’s survey and machine control specialist. "However, given the incidence of equipment theft on jobsites today, being able to do so without having to set up a single base station might be just as big. And finally, there is the significant cost savings realized by not having to invest in multiple base stations."

The total stations being used include a pair of Topcon GPT-9000 units and a QS-Series station, which features one-touch robotic setup, long-range reflectorless EDM technology and Advanced X-TRAC 8 for strong tracking and quick re-acquisition in challenging environments.

"The stations have been really helpful," says Cantu "We just purchased several GR-3 rovers to give to the grade checkers so they can move around freely, either checking grade behind the machines or staying out ahead and rough modeling. Now we can load a model into the data collector and any one of our guys can go anywhere on the site and have real-time grade within a millimeter. It was a bit of an investment, but again, it allows us to have one man doing that rather than a crew of three, so the savings over the long term are definitely there."