Central Corridor (Union Pacific Railroad)

Nevada

Proceeding east out of Winnemucca, the route follows the Humboldt River, in a directional running setup with the Overland Route until Wells, Nevada.^[1] From Wells to Salt Lake, the route, known as the Shafter Subdivision, loosely follows the historical route of the Hastings Cutoff, tunneling underneath the Pequop Mountains and crossing the Toano Range via Silver Zone Pass. The eastern approach to Silver Zone Pass features a horseshoe curve known as the Arnold loop. After crossing these mountain ranges the route proceeds southwest towards the Great Salt Lake Desert. In Nevada, Interstate 80 follows the Central Corridor, though the two routes are several miles apart in places.^[2]

Utah

The route enters Utah at Wendover and crosses the Great Salt Lake Desert and the Bonneville Salt Flats, parallel to Interstate 80 and the Wendover Cut-off, en route to the southern shore of the Great Salt Lake and Salt Lake City. Upon reaching Salt Lake City, the line turns south and follows the Jordan River through Point of the Mountain towards Spanish Fork.

After Spanish Fork, the rail line joins the U.S. Route 6 corridor, and the two follow each other towards Denver. Both routes follow the Spanish Fork (river) up a grade in the Wasatch Plateau, cresting at Soldier Summit. The western approach to Soldier Summit is known for the Gilluly loops, a series of horseshoe curves that allow the railroad to crest the mountains while maintaining grade that never exceeds 2.4%, unlike the highway, which was built using an older railroad grade, that features grades in excess of 5%.^[3] The railroad descends from Soldier Summit following the Price River until reaching the town of Helper, so named because in the era of steam locomotives, the railroad added or removed helper engines here for trains crossing Soldier Summit. Upon exiting the Wasatch Mountains, the train follows the southern rim of the Book Cliffs, in route serving the towns of Woodside, Green River (where the rail line crosses the Green River), Thompson Springs and Cisco. Near Cisco is where the rail line for the first time meets the Colorado River, which provides the path up the Rocky Mountains in Colorado. The rail line follows and crosses the river numerous times in Colorado while ascending the Rockies. Ruby Canyon is where the rail line reaches the state line.

Colorado

The railroad enters Colorado along the north bank of the Colorado River, following it to the Grand Valley, passing through the heart of Grand Junction and surrounding cities along the way. The tracks continue to follow the river out of the valley, routed along Debeque Canyon, Glenwood Canyon and Gore Canyon of the Colorado River towards Granby, Colorado near the headwaters of the river. The railroad departs the main stem of the Colorado river to follow the Fraser River, one of its tributaries until reaching the crest of the Rocky Mountains which is surmounted via the Moffat Tunnel. With the decommissioning of the route over Tennessee Pass, the Moffat Tunnel is the highest point on the Union Pacific system.^[4]

The eastern descent from the Moffat Tunnel towards the Front Range and Denver features 33 tunnels, leading to this portion being commonly called the Tunnel District. This portion of the tracks loosely follows Colorado State Highway 72, though at points the two corridors are in different canyons and several miles apart. Even past where the tracks exit the Rocky Mountains, the grade features horseshoe curves in the final descent. The tracks approach the Denver metropolitan area from the northwest, before merging with other rail lines just north of downtown Denver.

Role in Uinta Basin Rail project

The Central Corridor was at the center of controversy in 2022–23 due to the Uinta Basin Rail project in Utah, which would have added trains to the Corridor carrying waxy-crude oil. The project also proposed reactivating the Dotsero–Pueblo Tennessee Pass line (which had been out of service since 1997) to bypass the Central Corridor should it reach capacity.^[9]

Eagle County and environmental groups lobbied against the project, citing the increased risk for a major derailment and subsequent oil spill into the Colorado River (which runs along the Central Corridor) or the Arkansas River (which runs along the Tennessee Pass line).^[10][11] Eagle County's opposition to the project led to the Supreme Court ruling Seven County Infrastructure Coalition v. Eagle County, which focused on an appeal court's interpretation of the National Environmental Policy Act (NEPA) that had paused the project. In an 8–0 ruling, the court ruled against Eagle County, stating that potential environmental impacts outside the project's construction limits in Utah were not within the scope of an environmental impact statement as prescribed by NEPA.^[12]