B Line (RTD)

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.[2] Part of the FasTracks project, the first 6.2-mile (10 km) section from downtown Denver to south Westminster opened on July 25, 2016.[3] If fully built out, estimated around 2042,[4] 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.[2]

B Line
B and G lines bridge over rails and South Platte River.jpg
Bridge carrying B and G lines over freight lines and South Platte River
StatusOperating in truncated segment
OwnerRegional Transportation District
LocaleDenver metropolitan area
TerminiUnion Station
Westminster (initial)
Downtown Longmont (proposed)
8 (proposed)
WebsiteOfficial website
TypeCommuter rail
SystemRegional Transportation District
Operator(s)Denver Transit Partners
Rolling stockHyundai Rotem, Silverliner V
OpenedJuly 25, 2016 (2016-07-25)
Line length6.2 miles (10 km) (initial segment)
41 miles (66 km) (proposed)
Track gauge4 ft 8 12 in (1,435 mm) standard gauge
Electrification25 kV AC (60 Hz) overhead lines[1]
Route diagram

to Longmont
Downtown Longmont
SH 119 (Diagonal Highway)
SH 157 (Foothills Parkway)
Boulder Junction
SH 157 (Foothills Parkway)
SH 121 / SH 128 (
Church Ranch
SH 95 (Sheridan Boulevard)
US 287 (Federal Boulevard)
Fare Zone Boundary
Pecos Junction
41st & Fox
Union Station
Amtrak  A  G  N 
 C   E   W 


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;[5] this is completed in approximately 15 minutes.


Name Opening Year Interchange Municipality / CDP Park-n-Ride? Status
B Line (Union Station – Downtown Longmont)
Union Station 2014  A ,  G  &  N  Lines
 C ,  E , &  W  Lines
FREE MallRide (16th St)
Denver No Open
41st & Fox 2019  G  Line Denver Yes Open
Pecos Junction 2019  G  Line North Washington Yes Open
Westminster 2016 None Westminster Yes Open
Church Ranch TBA None Westminster Yes Proposed
Flatiron TBA None Broomfield Yes Proposed
Louisville TBA None Louisville Yes Proposed
Boulder Junction TBA None Boulder Yes Proposed
Gunbarrel TBA None Boulder Yes Proposed
Downtown Longmont TBA None Longmont Yes Proposed


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[6] in order to be completed prior to 2042.[4] 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.[7][8][4]

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.[9][10][11][12][13]

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.[14] 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.[15] 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.[4]


  1. ^ "Commuter train testing begins on G Line". RTD FasTracks. Regional Transportation District of Denver. Retrieved July 25, 2016.
  2. ^ a b "RTD - B Line". Regional Transportation District. Retrieved June 22, 2015.
  3. ^ Villanueva, Raquel; McGill, Nick (25 July 2016). "RTD unveils B-Line in Westminster". TEGNA, NBC. 9News KUSA-TV. Retrieved 25 July 2016.
  4. ^ a b c d Aguilar, John (24 January 2020). "Non-RTD solution to Boulder's long-missing train draws hope, skepticism". Denver Post. Retrieved 27 January 2020.
  5. ^ "RTD - Northwest Rail Line - Project Map". Regional Transportation District. Retrieved February 11, 2015.
  6. ^ Regional Transport District. "Northwest Corridor FAQ". Regional Transport District. Retrieved 22 April 2013.
  7. ^ Whaley, Monte (August 10, 2012). "RTD officials face legislative grilling over commuter rail delay". The Denver Post. Retrieved 22 April 2013.
  8. ^ Thomas, Dillon (10 August 2018). "Boulder County Cities Want Share Of FasTracks". CBS4 Denver. Retrieved 19 August 2018.
  9. ^ "Boulder council: RTD proposals have broad impacts". Boulder Daily Camera.
  10. ^ "Boulder concerned about RTD transit plan along U.S. 36". Boulder Daily Camera.
  11. ^ "RTD proposes cut of direct Boulder service". The Denver Post.
  12. ^ "U.S. 36 reconstruction ongoing as is branding plan". The Denver Post.
  13. ^ Whaley, Monte (February 4, 2013). "RTD foots bill for study of northwest transit system, cities sign on". The Denver Post. Retrieved 22 April 2013.
  14. ^ Fryar, John. "Area cities consider funding rail service to Longmont". Colorado Hometown Weekly. Retrieved 19 August 2018.
  15. ^ Minor, Nathaniel. "Heard Chatter About A Bare-Bones RTD Train To Boulder? Don't Hold Your Breath". Colorado Public Radio. Retrieved 2019-05-10.

External linksEdit

Route map:

KML is from Wikidata