RTD is going ahead with plans to build a single-track light-rail line on the last leg of the FasTracks West Corridor line despite lack of agreement from Jefferson County officials.

"At this point, we've got to make a hard decision," RTD General Manager Cal Marsella told the elected board's planning and development committee Monday. "We are really up against it right now."

RTD has to finalize details this month for the 12.1-mile light-rail project between Denver's Union Station and the Jefferson County government center in Golden to meet a deadline for applying for a federal grant.

"If we don't get the fed grant, there would be no corridor whatsoever," Marsella said.

The project originally included two tracks on that final segment. But in 2005, faced with cost increases, RTD decided to cut service on the outer leg to trains every 15 minutes instead of every five minutes. That allowed RTD to reduce the number of train cars it had to buy, saving more than $12 million.

Then last year, with costs still escalating sharply, RTD realized it could run 15-minute service on a single track west of the federal center by including a short passing track near Red Rocks Community College. The move saved another $33 million.

Jefferson County planners and commissioners objected, saying if RTD's ridership estimates are wrong and more growth occurs than anticipated, RTD would be locked into having inadequate track capacity to handle it.

Jeffco had asked RTD to consider running 10-minute trains, which would have required a second passing track.

Jeffco Commissioner Kevin McCaskey said the county will push for the second passing track before the RTD board makes a final decision this month.

"We feel the voters were promised a higher level of service," -McCaskey said.

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