The Illinois Department of Transportation (IDOT) has kicked off the installation process for the Continuously Operating Reference Stations (CORS) network, which will help improve the accuracy of location data used for surveying, mapping, construction, and engineering, as well as a host of other applications.
The CORS network is a series of fixed monuments that serve as reliable reference points to continuously record and transmit 3D location data to satellites and other receivers in the area, enabling them to determine their position with greater precision.
Once the installation process is completed, there will be approximately 70 sites statewide, forming a dense, public spatial network that connects to a Global Navigation Satellite System. These new sites will join roughly 2,000 others across the country that make up the fabric of the national CORS network that supports Geographic Information System applications and other uses.
IDOT stressed that the potential benefits and users are vast and not limited to the proposed initial uses of the network.
“Surveyors can tie into this as a benchmark as a very known and very accurate survey monument. They’re able to use that information to strengthen the accuracy of their projects,” said Dan Mlacnik, engineer of Surveys, Mapping, and Modeling in the Bureau of Design and Environment, which is behind the effort for IDOT.
In addition to surveying, the technology can be used for other activities, ranging from automated planting and harvesting to Illinois State Police crash reconstructions. The CORS network also measures tectonic plate movement and will provide valuable information to NOAA’s surveillance for the National Geodetic Survey. IDOT stressed that this is especially important with the New Madrid fault and seismic zone crossing Illinois.
The inconspicuous structures, known as driven-braced monuments, are permanent, deeply anchored tripodal fixtures made of stainless-steel rods drilled 12 feet into the ground at precise angles. Antennae located within the structures are protected by a dome to prevent damage from the elements. The structures are being installed by IDOT’s in-house construction team.
Before determining install locations, IDOT considered roughly 120 of its properties, including maintenance yards, weigh stations and rest areas. To be selected, sites had to meet specific requirements, including a clear view of the southern sky to tie into the constellations of satellites overhead. Survey units and survey chiefs in each district helped to determine whether proposed sites met the requirements. Additionally, the Bureau of Information Processing helped procure all the backend infrastructure needed to power the network.
Funding for the project came from the Federal Advanced Digital Construction Management Systems grant awarded to IDOT in 2023, as well as matching state funds.
“The Illinois CORS network will be available to the public – we’re creating a new public utility,” said Cassidy Weller, a GIS support technician. “If you have a piece of surveying equipment, if you have a piece of heavy machinery that has automated machine guidance of any kind, whether it be an end loader or a bulldozer or John Deere tractor, if it has this capability where you can press a button and have it follow some sort of preplanned route, you can tie into our network and have it be dead on.”
