The Regional Transportation District board on Tuesday unanimously approved a plan to build a hybrid system of transportation — part commuter rail and part bus lines — to the northwest corridor from Denver to Longmont instead of a full rail system voters were promised in 2004.

The vote came following a litany of rhetoric praising the work of staff and others who devised the combination transportation plan — even with some expressing mild concern voters might defeat an additional tax increase in November to build it.

“The economic downturn extended the north lines the most and is forcing us to ask voters for an additional tax increase,” RTD board member Bill James said.

“While support is fragmented, I’m gratified the citizens are joining in the realization that we’re all in this together.”

Following weeks of public hearings in which citizens from several communities said they worried rail would never reach them, the hybrid plan promises Bus Rapid Transit from Westminster to Longmont and a commuter rail from Denver’s Union Station to Church Ranch Road.

The entire option hinges on voters approving a doubling of a 0.4 percent sales tax in November — but that issue may not even get to them. The plan now moves on to the Denver Regional Council of Governments, which has the authority to approve or kill the measure. It’s expected that body will decide on the matter by June.

Before DRCOG will be:

• Commuter rail — diesel-powered trains, not electrified light rail — at a cost of about $400 million, to be in place by about 2022.

• Bus Rapid Transit costing about $894 million to Longmont with a promise not to change service for at least five years, to be finished by 2020;

• A promise to pursue all funding sources to build out the rail line as it’s available, likely by 2028.

Should a vote fail — or if it’s refused by DRCOG — the plan to bring rail to Longmont would continue, but with a finish date unlikely until about 2042.

The hybrid option has met with a mixture of concession and resistance, mostly wedged in the issue of a sales tax increase approved in 2004 by voters to pay for the FasTracks system.

At a handful of public meetings, citizens and public officials alike voiced concern that their vote favoring a 0.4 percent sales tax carried with it a promise that commuter rail to the northwest corridor — from Denver to Longmont — would be delivered.

General Manager Phil Washington has said RTD isn’t backing away from the promise, but noted that revisions to a variety of financial plans and estimates means Longmont wouldn’t see rail until about 2042.

Stunned, residents from Westminster to Boulder and upward into Longmont have said in force that they’d fight for what they paid for. But they’ve also said they’d do whatever necessary to get rail where it’s been promised.

The hybrid option takes on a pair of issues — the speed of getting commuter service to the corridor and the long-term desire to make sure it’s in the shape of a train.

“This is not just a Longmont issue or just a northwest corridor issue,” board member Lorraine Anderson said. “It’s a whole-region issue. The board in the past has stepped back from seeking a sales tax increase, but we all know in order to complete FasTracks in a timely fashion we all need to move ahead.”

David Migoya: 303-954-1506 or dmigoya@denverpost.com