Underground Transmission Line and Overhead-to-Underground Transition Structures

The new transmission line that is needed to provide power to the Thornton Substation will be constructed underground. Construction within the roadway will require lane closures and slower traffic patterns along Holly Street, East 119th Avenue and East 112th Avenue in areas identified on the map below.

Transmission Line Construction Map

Click on the map to view a larger version of the transmission line construction zone map.

Transmission Line Consruction
Watch a short animated video showing the steps of underground transmission line construction


Prior to starting construction of the underground transmission line, survey crews will confirm the location of underground utilities and other infrastructure. Crews will then dig a trench and the transmission line will be placed in a concrete-encased duct bank. Precast concrete maintenance vaults will be installed at points along the route to give workers access by manholes for construction and maintenance. The trench will then be refilled and the roadway will be repaved.

Two new overhead-to-underground transition structures will be constructed just west of the intersection of 112th Avenue and Riverdale Road. These structures will interconnect the new underground transmission line to the existing Fort Lupton-Cherokee transmission line.

Photo simulations from the Skylake Ranch neighborhood show what the transition structures will look like.

During underground construction, you may experience the following:

  • Partial or full road closures
  • Traffic control measures, such as flaggers and detour signage
  • Temporary changes to neighborhood or property access
  • Construction noise

Measures will be taken to reduce these construction impacts. Once construction has been completed in an area, it will be restored to its previous condition.

Xcel Energy employees and contractors will maintain traffic control to allow for a safe work area while providing drivers, cyclists and people on foot with the safest possible routes around the construction area.

Click here for updates on road closures and construction progress.