N Line (RTD)

The possibilities and studies for a rail line in the North Metropolitan Denver have existed since the opening of the Light Rail Central Corridor in 1994. In the 2004 election year voters approved the North Metro Corridor as part of the RTD FasTracks expansion plan. In September 2006 the Environmental Impact Statement (EIS) was started, with completion in late 2010, and gaining approval by the Federal Transit Administration in April 2011.^[7] A preexisting railroad right-of-way for the line was purchased in 2009. The contract to build the North Metro Rail line to 124th Avenue was awarded to Graham, Balfour Beatty, Hamon Constructors (GBBH) in November 2013 with notice to proceed in December 2013.^[8] The GBBH contract included an option that when funding is available RTD can exercise the option to build the line to 162nd Avenue.

Groundbreaking of the N Line's construction occurred on March 20, 2014^[9] with an expected completion date in 2018. The GBBH joint Venture is operating under the name Regional Rail Partners (RRP).^[10] By August 2018, construction on the line was 85% complete, but the estimated completion had slipped to late 2020 or early 2021;^[6] the start of revenue service had again been delayed several months by September 2019.^[11] Despite slowdowns caused by the COVID-19 pandemic, the line opened on September 21, 2020.^[2][12]

The N Line's northern terminus is at Eastlake/124th station, the site of a historic grain elevator in Eastlake. The line continues south before arriving at Northglenn/112th station before turning southeast near East 112th Avenue before reaching Thornton Crossroads/104th station. The line then curves southwest before reaching the Original Thornton/88th station. The line then curves southeast again, passing over the South Platte River, under State Highway 224, and under Interstate 76 before reaching Commerce City/72nd station. The line then curves southwest, eventually rising over the Skyway Bridge, crossing over Interstate 270, Sand Creek, and various railroads and industrial areas before returning to at-grade on the southeast side of Riverside Cemetery. The line continues southwest along the Union Pacific / BNSF corridor, reaching the 48th & Brighton/National Western Center station located near the National Western Stock Show complex, crossing under Interstate 70 and over the South Platte River twice and besides rail yards, near Coors Field before entering Union Station in Denver. It runs mostly on a preexisting railroad right-of-way to its northern terminus at Eastlake/124th station.^[13][14][15] A notable exception to using the existing railroad right-of-way is the RTD designated "Skyway Bridge" whose single-tracked path takes it over and past several obstacles: the BNSF Railway railroad tracks, Brighton Boulevard, a Union Pacific Railroad spur track, the Farmers Reservoir and Irrigation Company (FRICO) Ditch, the Metro Waste Water Plant and Suncor oil processing site, Sand Creek, and Interstate 270.^[5]

In 2004 Colorado voters approved FasTracks, a multibillion-dollar public transportation expansion plan. In 2009 RTD paid $117 million ($176 million adjusted for inflation) to purchase the right-of-way from Union Pacific in preparation for the build-out of the North Metro rail line. Budgeting issues set back FasTracks plans, including those for the N Line. Construction of the line was able to proceed when RTD partnered with a private firm to build the line in 2 stages. The first stage will build the line to the 124th Avenue Station with an opening in 2020, while the second stage to North Thornton/Hwy 7 station will commence when projected ridership makes economic sense.^[17]