TransWest Express is a 732-mile, high-voltage transmission system being developed in the US. Credit: nieriss/
The TransWest Express line will extend from Wyoming to Nevada via Utah. Credit: Business Wire.
The transmission line will connect the Chokecherry and Sierra Madre onshore wind power project to existing grids in Wyoming, Utah, and southern Nevada. Credit: Slava Stock/

The TransWest Express project is a 732-mile (1,178km), high-voltage inter-regional transmission system under construction in the US. It is being developed by TransWest Express, a wholly-owned subsidiary of US-based private holding company Anschutz.

The multi-state transmission line will transmit up to 3GW of clean electricity produced in Wyoming to Utah, Arizona, Nevada and California.

Construction of the project was officially launched with a ground-breaking ceremony held in June 2023.

Scheduled to commence operations in 2027, the TransWest Express transmission line is expected to deliver up to 20,000 GWh of low-cost renewable electricity a year across the Western US power grid.

The high-voltage, interstate transmission infrastructure is estimated to cost $3bn. It is being developed in line with the US vision of a carbon-free electric grid by 2035.

TransWest Express route details

The transmission line will extend from a northern terminal located near Sinclair in southern-central Wyoming and cross through northwestern Colorado and central Utah to a southern terminal located 25 miles south of Las Vegas in southern Nevada. About two-thirds of the project’s route lies on federal lands.

TransWest Express project development details

The project development was originally undertaken by the Arizona Public Service Company, the National Grid and the Wyoming Infrastructure Authority.

Anschutz formed TransWest Express and took over the development rights of the project in July 2008.

The plan of development for the project was submitted to the US Bureau of Land Management in January 2009.

The Western Area Power Administration joined BLM as the lead agency for preparing the environmental impact statement for the project in 2010. The record of the decision finalising the route of the power line was issued in 2017.

TransWest Express was identified as critical transmission infrastructure by US federal agencies including the White House Council on Environmental Quality, the Department of the Interior and the Department of Energy in 2011.

The governors of Wyoming, Utah, Nevada and California signed a memorandum of understanding (MoU) for the interregional transmission project in April 2015.

The State of Wyoming’s Industrial Siting Council permitted TransWest Express to construct and operate the project in April 2019.

BLM issued a notice to proceed with the construction of the line in April 2023.

TransWest Express project design and components

The TransWest Express transmission line will feed electricity generated by the 3GW Chokecherry and Sierra Madre wind power project under construction in Carbon County, Wyoming, to the existing grids in Wyoming, Utah and southern Nevada.

The main components of the transmission line include a 405-mile, 525kV high-voltage direct current (HVDC) segment capable of transmitting 3GW of electricity between Wyoming and Utah, a 278-mile, 500kV high-voltage alternating current (HVAC) segment capable of transmitting 1.5GW of electricity from Utah to Nevada, and a 49-mile 500kV HVAC transmission line in Nevada.

The project also includes the construction of two HVDC converter stations along with ground electrode facilities in Wyoming and Utah, four alternating current substations in Wyoming, Utah and Nevada, and a fibre optic network communications system.

The TransWest Express line is planned to be interconnected to PacifiCorp’s 500kV transmission system in Wyoming, to the  Intermountain Power Agency’s 345kV switchyard at the Intermountain power project in Utah, to NV Energy’s 500kV system and to the California Independent System Operator’s 500kV transmission system in Nevada.

Contractors involved

Barnard Wilson Joint Venture, a partnership between Barnard Construction and Wilson Construction, was selected to construct the TransWest Express transmission line and associated substations in June 2023.

Siemens Energy was contracted to supply the HVDC converter stations for the project in December 2022.