With the estimated cost of the FasTracks transit program ballooning Thursday to $7.9 billion - far beyond the reach of the revenue to pay for it - RTD officials plan to take their plight to the public.

They are looking at three choices:

* Slow completion of some of the lines to keep costs within the current tax revenue, which would add five to 17 years of construction.

* Eliminate some of the lines to finish others within the current tax and nine-year completion schedule.

* Seek an additional tax hike, perhaps packaged with a statewide highway funding initiative.

Delaying or trimming some corridors would be politically explosive because it would deny some communities the service they were promised when voters approved the original plan.

"We're willing to work with RTD but they made certain promises to voters and they have to keep them," said Thornton Mayor Erik Hansen, whose city sits astride one of the potentially delayed corridors, North Metro commuter rail.

"This is just a fundamental issue of equity."

"I don't want to beat up on RTD because government entities around the country are struggling with finances," added Boulder Mayor Shaun McGrath. "But it is important for us in Boulder to

really try to get to the vision that the voters had in mind."

Some lines 'crucial'

Two of the three options involved delaying or possibly not even building rail lines to transit- friendly Boulder-Longmont, Commerce City-Thornton, an extension of the T-REX line up Interstate 225 in Aurora and extensions of existing light rail into Lone Tree and Highlands Ranch.

Under those two scenarios, the only corridors guaranteed for on-time completion would be the West Corridor light rail to Lakewood-Golden, already under construction contracts, and the electrified commuter lines to Denver International Airport and Arvada-Wheat Ridge.

RTD General Manager Cal Marsella said going with the airport and Arvada lines is crucial because, along with West, they are the only new FasTracks corridors eligible for federal funding. Canceling or shortening them would cost RTD $1.3 billion in anticipated federal funds.

But hit with a lot of push-back from local officials since he disclosed the problem with financing last month, Marsella said he wants to find a way to do all the lines on the original timetable.

"We will put on a full-court press to build the whole program," Marsella said.

FasTracks opponent Jon Caldara, however, offered up a fourth option: Repeal FasTracks at the polls. "We are in preliminary discussions on how to bring forward a recall of this failed plan," said Caldara, head of the Independence Institute in Golden, who said during the 2004 FasTracks campaign that the costs were bound to soar.

Soar they did.

The original $4.7 billion cost ballooned to $6.1 billion last year. Now, RTD staff says, finishing the original plan by 2017 would cost $7.9 billion, and the current sales tax trend won't produce that much money by then.

The latest cost is nearly 30 percent higher than last year's estimate and 68 percent higher than when voters approved a tax increase for it in 2004.

It could get worse.

"If someone asked me, 'How confident are you in that number?' I have to say I can't really give you an ironclad guarantee," Marsella said.

Caldara said opponents will wait until RTD chooses which option it will pursue before he decides whether to challenge it. State law permits voters to rescind the FasTracks tax except for whatever portion is needed to pay off any obligations already incurred.

Since last month, Marsella has tried to share the responsibility for the FasTracks program with other agencies that vetted the financial assumptions and OK'd them. That included several independent evaluations of FasTracks' cost assumptions and projections, which went south a year after the vote when construction costs started to soar.

Mayors weigh in

RTD plans to seek comment on the three strategies, first outlined in July. Marsella said Thursday that in addition to meetings with transportation agencies, elected officials and others, it would also hold public hearings in each of the 15 districts within its borders.

The goal is to recommend a course of action to the elected RTD board on Nov. 4.

"I've heard about options A, B and C, and none of them works for us," said Mayor Ed Tauer of Aurora, which faces the delay of the Interstate 225 light rail extension from Parker Road to Interstate 70. It would serve the growing Fitzsimons medical campus.

"I want to hear what option D is. For metro taxpayers, FasTracks success means delivering what you promised."

The agency blames the problem on a sharp escalation in construction costs and declining sales tax collections, a key part of FasTracks' funding.

RTD's staff analysis says that if it were to postpone some lines but build the airport and Arvada lines, it would cost $5.9 billion by 2017.

flynnk@RockyMountainNews.com or 303-954-5247

The rising cost of FasTracks

$4.7 billion

* Voters approve the sales tax increase in 2004.

$6.1 billion

* RTD revises the estimate 30 percent upward in 2007 after several years of record cost increases in construction materials.

$7.9 billion

* RTD's annual review this year adds another 30 percent on top, citing more unexpected construction inflation.