GDT > Projects > Northwest Rail

Completing the B Line to Boulder, Longmont and beyond…

Promised in the RTD FasTracks sales tax vote in 2004, the 41 mile Northwest Rail Line is intended to connect Denver to Boulder and Longmont via commuter rail. However, it has experienced several delays and challenges in development including cost increases that RTD has struggled to find ways to fund.

The original plan was to pay BNSF, who own the tracks from Westminster to Longmont via Boulder, to double-track the line and electrify it at 25kV AC, which is what the rest of the RTD commuter rail system uses. While the double-tracking wasn’t such a deal for a large Class I railroad, the electrification was asking BNSF to do something it had practically zero construction and operating experience in return for no benefit for freight train operations, which would remain diesel powered.

The result was that the costs quoted ballooned from the $461m original estimate to complete the northwest rail one in 2003 (before the FasTracks vote) to $1.5bn in 2018. With polling showing that voters were unlikely to approve further sales tax increases, RTD started projecting that they wouldn’t have funds to complete the line until 2042 (now revised to 2044). These dates are clearly unpalatable for politicians in Boulder and Longmont, who point out that their communities have now been paying their fair share of FasTracks sales taxes for 20 years with little progress on the line to show for it.

Because of the issues, the uncompleted B line to Boulder and Longmont remains the No. 1 source of ammunition for RTD’s detractors who accuse the agency of breaking its promises to communities located northwest of Denver and wasting taxpayers cash.

The current B Line service…

Currently, only the first 6 miles of the B Line between Union Station and Westminster have been completed with trains running on a dedicated electrified single track in a shared right-of-way with BNSF. This section opened in 2016 and offers an hourly service, all-day, seven days a week. Ridership has never necessitated the operation of more than a 2-car commuter train consists and the line suffers a poor station area layout at Westminster that makes connections to bus services inconvenient. In addition the transit orientated development (TOD) has so far failed to significantly materialize around the station and due to the low service frequency, most park-n-ride customers will opt to drive to one of the G Line stations a few miles south which currently enjoy double the number of trains.

RTD Peak Service Study

In 2022, the RTD Board of Directors authorized the study to respond to stakeholder input on how RTD might complete its 2004 FasTracks Plan by assessing an initial commuter rail service in the Northwest Corridor. The study advances the concept brought forward from local stakeholders and RTD staff with a specific focus on developing a “common set of facts” to inform the RTD Board of possible next steps.

The project team began the study with the basic service concept defined by stakeholders and the Board. The peak service concept is three trains in the morning from Longmont to Denver Union Station and three trains in the afternoon from Denver Union Station to Longmont. The study then went on to identify corridor and regulatory challenges and constraints, infrastructure requirements, fleet (train vehicle) options, station site plans, platform configurations, concept designs, and the range of costs, benefits, and impacts of providing the service.

Finally next steps, such as how to collaborate with the Front Range Passenger Rail District were identified.

How will the peak service concept work?

The basic concept comprises of RTD operating three peak services at 30-minute intervals from Longmont to Denver Union Station (DUS) in the morning with return trips in the evening. The trains would use BNSF tracks from Longmont to Westminster and then complete their journey into DUS using RTD’s existing B Line commuter rail tracks. During the day the trains would lay over at new sidings at Westminster, substituting for current B Line services on both their trips in and out of DUS.

Journey time from Longmont to DUS is planned to be 65 minutes, plus or minus two minutes which is competitive with driving.

To accommodate both passenger and freight trains, the railroad is divided into operating periods, referred to as time blocks, where either BNSF or the commuter rail operator are running trains. During the 3-hour commuter rail time blocks, freight trains within the corridor would be directed to and held in one of the freight sidings until commuter services were completed. The freight train would occupy the siding while passenger trains operate on the route.

This very simplistic solution reminds us of when we were kids and had to share the train set. Child A would run their freight train for a bit and then take it of the track so child B could have a turn running their passenger train. After 3 hours, child A would then get another turn and so on…

What infrastructure upgrades are required?

The peak service calls for six new stations, equipped with high-floor platforms to match those already used on RTD’s commuter rail system. These will need to built with separate sidings to allow freight trains to pass by without striking the platforms.

BNSF identified four freight passing sidings required to maintain freight rail service in the corridor. The four sidings were consolidated into three sidings with capacity to hold four freight trains to minimize roadway crossing impacts as BNSF developed its concept designs. Three freight passing sidings are required along the corridor and will be located at:.

• Between Old Wadsworth and US 36 (Westminster) – approx. 1.85 miles long
• Between Baseline Road and 55th Street (Louisville and Boulder) – approx. 4.84 miles long
• Between North 55th Street and North 63rd Street (Gunbarrel) – approx. 1.47 miles long

This joins two existing sidings located at:

• Between Nickel Street and Brainard Drive (Broomfield and Interlocken) – approx. 1.79 miles long
• Between Boulder Creek and Pearl Parkway (East Boulder) – approx. 0.73 miles long

What will the trains be like?

What are the anticipated costs?

Joint Service Proposals

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