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CORS gives accuracy to global positioning

Lewis and Clark wouldn’t have needed a compass or sextant had they been crossing the Bitterroot Mountains today. They could have taken advantage of a location transmitter recently installed in ITD’s District 6 to find their way to the Pacific.

A new receiver, located at the Driggs maintenance yard, was powered up without much fanfare recently. But its impact will be far reaching.

Users who depend on locating technology to make their jobs easier and more accurate are look forward to using the new CORS (Continuously Operating Reference Station) system that is mounted on a permanent concrete base. It is based on Global Position Satellite technology.

The receiver collects satellite data 24 hours a day and determines a highly accurate position (latitude and longitude) on the earth, according to Rayce Ruiz, land surveyor for ITD District 6 in Rigby. The data can be accessed via the Ethernet by GPS users.

“The CORS is a reference used to correct observed GPS data for higher accuracy,” Ruiz explained. Several groups of users, including surveyors, geologists, engineers, Geographic Information Systems (GIS) users, emergency medical service personnel, earth moving equipment and farmers access CORS data for the higher accuracy.

Besides using the Ethernet, a UHF radio can be linked with the CORS. The radio broadcasts a correction to enable the GPS user to get Real Time Kinematic(RTK) positioning.

“Our Location section will use this RTK capability to perform our surveys in the Driggs-Victor area,” Ruiz said.

The CORS in Driggs is one of three stations that will be installed at locations throughout District 6 in partnership with universities or special projects. CORS is part of the statewide Intelligent Transportation System (ITS). Stations will be added at BYU-Idaho in Rexburg and at Idaho State University’s Idaho Falls facility.

The CORS at BYU was funded through the Menan-Lorenzo Interchange project. ITD was looking for a close government or educational site to install the station, Ruiz said.
“We could not donate the funds to a private company for a site,” he explained. “BYU-Idaho is in the vicinity of the project, so I approached the university and asked it to be a partner. The CORS will be used during the design and construction of the interchange.”

Funds for the CORS at ISU in Idaho Falls were tied to the St. Leon Interchange project in a similar way. The university uses GPS as an educational tool and training in its classes.
As director for the Eastern Section of the Idaho Society of Professional Land Surveyors, Ruiz has been working on CORS for about two years, coordinating the installation of CORS with local land surveyors.

He says applications for CORS vary by user. Surveyors want the RTK feature. GIS users want GPS for mapping. Geologists locate rock formations and seismic spots. Earth movers use GPS to set grades. Farmers use GPS to plow the rows in their fields.
Ruiz will use CORS in his survey work for ITD.