WASHINGTON -- The cost of building a government railroad across rural Nevada to carry nuclear waste to Yucca Mountain has grown beyond $3 billion and is climbing with groundbreaking still several years away, according to new estimates.

The Department of Energy has set $3.155 billion as the latest price tag to run rail about 319 miles from Caliente in Eastern Nevada to the Yucca site in Nye County.

A previous cost estimate, disclosed in December 2005, was $2 billion.

The numbers underscore the growing cost of the proposed Nevada nuclear waste complex, and the likely challenges facing the Energy Department to secure funding from Congress for the undertaking.

"I think this is going to be a big pill to swallow on Capitol Hill," said Bob Loux, executive director of the Nevada Agency for Nuclear Projects. "This goes to show the longer things get delayed the more expensive it will be for the rising costs of concrete and steel. But also that this is a more difficult job than they thought before."

The Energy Department in March estimated that repository construction and transportation, and initial operations at the site, would cost $27 billion. The department has not updated broader and longer range "life cycle" costs, which were at $57.6 billion in 2001.

The government still is several years away, at least, from breaking ground for a railroad and for waste-handling buildings beyond the five-mile long wide-mouth exploratory tunnel and study facilities at the site already.

Project Director Ward Sproat, at a meeting on Friday with Nevada county officials, said that railroad groundbreaking likely will be delayed beyond 2009, according to several meeting participants.

Sproat told the meeting he was not sure if the rail project would have the funding to start by then, officials said.

DOE has routinely steered money from Yucca transportation segments to complete a license application that is considered to be a more pressing priority.

A 54-page draft national transportation document containing the new railroad cost estimates was circulated last week among state and local officials, potential repository vendors and other stakeholders.

DOE spokesman Allen Benson said the new dollar amounts for a Nevada railroad are based on "a better understanding of the cost of facilities, understanding there was a lot more work done on (the plan) and we have had a better look at the costs.

"As we come closer to construction we will have to update the costs. This is where we are at this point." The rail cost estimates include features such as an equipment yard, maintenance facilities, a train control center and sidings to connect the line to existing track in Caliente, according to the DOE transportation document.

Bob Halstead, a transportation consultant under contract to the state, said DOE's estimate still might be low.

"Not knowing what went into these numbers but having done detailed cost exercises and having revisited the numbers to adjust them I would say these DOE numbers seem credible but they still might be too low. The high number could be $3.6 billion or $3.7 billion," Halstead said.

Halstead also said as the rail costs continue to grow, DOE may come under pressure from trucking companies to abandon rail and ship nuclear waste to the Yucca site by truck as a more economical choice.

That scenario would open a host of new controversies, though, as the most likely truck routes would traverse the populated Las Vegas valley, he said.