B Line (RTD)

"Northwest Rail Line" redirects here. For other uses, see North–West line.

The B Line, also known as the Northwest Rail Line during construction, is a commuter rail line which is part of the commuter and light rail system operated by the Regional Transportation District in the Denver metropolitan area in Colorado.^[3] Part of the FasTracks project, the first 6.2-mile (10 km) section from downtown Denver to south Westminster opened on July 25, 2016.^[4] If fully built out, estimated around 2042,^[5] the B Line will be a 41-mile (66 km) high-capacity route from Denver Union Station to Longmont, passing through North Denver, Adams County, Westminster, Broomfield, Louisville and Boulder.^[3]

B Line
B Line train at Westminster Station
Overview
Owner	Regional Transportation District
Locale	Denver metropolitan area
Termini	Union Station Westminster (initial) Downtown Longmont (proposed)
Stations	4 10 (proposed)
Service
Type	Commuter rail
System	RTD Rail
Operator(s)	Denver Transit Partners
Rolling stock	Hyundai Rotem Silverliner V
Ridership	157,000 (FY2023, annual)[1]
History
Opened	July 25, 2016; 8 years ago (2016-07-25)
Technical
Line length	6.2 mi (10.0 km) 41 mi (66 km) (proposed)
Track gauge	4 ft 8+1⁄2 in (1,435 mm) standard gauge
Electrification	Overhead line, 25 kV 60 Hz AC[2]
Route map B Line highlighted in green Show interactive map Legend extension to Longmont (TBD) Downtown Longmont SH 119 Diagonal Hwy Gunbarrel SH 157 Foothills Pkwy Boulder Junction SH 157 Foothills Pkwy Louisville Northwest Parkway Flatiron SH 121 Wadsworth Blvd Church Ranch US 36 SH 95 Sheridan Blvd Westminster US 287 Federal Blvd I-76 to Wheat Ridge/Ward Pecos Junction CRMF I-70 41st & Fox I-25 South Platte River to Eastlake/124th to Denver Airport Amtrak California Zephyr Union Station This diagram: view talk edit Show route diagram

Route

The B Line's southern terminus is at Union Station in Denver. It runs on a railroad right-of-way north sharing track with the G Line until Pecos Junction station, after which the two routes diverge. Initially, the B Line continues north to its terminus at Westminster station;^[6] this is completed in approximately 15 minutes.

Stations

Station	Municipality	Opened	Major connections & notes
Union Station	Denver	April 22, 2016	California Zephyr MallRide Flatiron Flyer
41st & Fox		April 26, 2019	Park and ride: 500 spaces
Pecos Junction	North Washington		Park and ride: 300 spaces
Westminster	Westminster	July 25, 2016	Park and ride: 350 spaces
Downtown Westminster		—	Proposed[7]
Broomfield - 116th	Broomfield	—	Proposed[7]
Flatiron		—	Proposed[7]
Downtown Louisville	Louisville	—	Proposed[7]
Boulder Junction	Boulder	—	Proposed[7]
Downtown Longmont	Longmont	—	Proposed[7]

FasTracks

Main article: FasTracks

In 2004, Colorado voters approved FasTracks, a multibillion-dollar public transportation expansion plan. As part of the Eagle P3 project, the first segment of the B Line opened on July 25, 2016. The remaining segment, extending to downtown Longmont, will require additional funding^[8] in order to be completed prior to 2042.^[5] The announcement angered many voters in the cities and suburbs north of Denver, who had approved a sales tax increase in 2004 to fund the FasTracks project.^[9][10][5]

The downturn in the economy, poor cost projections that significantly underestimated construction costs and other reasons led to the initiation of the year-long "Northwest Area Mobility Study" for what was then known as the Northwest Rail line. Out of this study came an agreement between northwest area governments and transportation partners to build a line very different from what the lines voters originally approved. The study concluded in 2014. It made a number of recommendations that were adopted by the RTD.^{[11][12][13][14][15]}

In summer 2018, the U.S. 36 Mayors and Commissioners Coalition was gathering support from other members to ask RTD to provide an estimate for at least weekday rush hour commuter rail service along the original corridor to Longmont.^[16] In spring 2019, Longmont City Council asked RTD to look into the barebones "Peak Service Plan". RTD estimated a start-up cost of $117 million, serving an initial weekday ridership of 1,400. By mid-2019, completion of the full original line was estimated at $1.1-1.5 billion (in 2013 dollars), targeted for 2042, 25 years after the original planned opening.^[17] In early 2020, RTD estimated it could construct the rest of the line for peak-direction service at a cost of $700-800 million; full-day service would not be expected until 2050 at a final cost of $1.5 billion.^[5]

Northwest Rail Peak Service Study

The Peak Service Study is an ongoing analysis of what a minimum service to Longmont could look like, as an interim step until the line is fully built out as called for in FasTracks. While not expected to conclude until the end of 2023, the study has so far suggested adding six additional stops past the current Westminster terminus, serviced by three southbound morning trips, and three northbound evening trips.

In contrast to the rest of the RTD commuter system, this minimum service would operate on shared track with BNSF freight trains, and rely on new and existing sidings for holding freight while commuter trains are passing. This shared extension would notably use diesel locomotives instead of overhead electrification as the rest of the system uses.^[18]