Plans to route a proposed extension of the Washington, D.C. Metropolitan Area Transit Authority rail line through a tunnel in Tysons Corner, Va., have collapsed under political pressure. Virginia Gov. Tim Kaine announced Sept. 6 that the state will move forward with an existing aerial alignment instead of a tunnel option for the Tysons Corner segment of the Dulles corridor Metrorail project � a 23-mi., $4-billion plan that would extend metro service from Falls Church, Va., to Dulles International Airport.

The decision came nearly five weeks after a review panel of engineers touted the benefits of a 0.4-mi. tunnel through the congested Tysons Corner area. After a Sept. 6 meeting with Federal Transit Administration chief James Simpson and several Virginia representatives on Capitol Hill, Kaine announced that the tunnel alternative presented too many risks.

"We carefully reviewed the tunnel option at Tysons, and I share the belief of many of our project partners that a tunnel alignment would be the best option," he says. "However, too many unanswered questions remain about cost and timing. These uncertainties cannot be allowed to jeopardize this critical project."

In July, Rep. Frank Wolf (R-Va.) and Rep. Tom Davis (R-Va.) sent a letter to Gov. Kaine warning that delays associated with a new environmental study and resulting cost increases could endanger federal funding of the project.

"We have been repeatedly told by the Federal Transit Administration that, according to federal regulations, if a transit project exceeds federal cost-benefit standards, the project is ineligible for federal funding regardless of whether a local, state or private entity may be willing to pay the cost difference," according to the letter. "This could mean that the federal government's share of the project - up to $900 million - could not be tapped. The Commonwealth may very well be rolling the dice on the future of this project."

Wolf and Davis suggested that the tunnel plan could set the project back by as much as two years.

In recent meetings with FTA officials, other potential risks became clear, according to Davis aides. The Metrorail extension was given an exemption from certain FTA standards under legislation passed in Congress. Changes to the basic design of the project would have nullified that deal and potentially forced Davis and other Virginia representatives to go back and seek a new exemption, says Dave Marin, spokesman for Rep. Davis.

"If that exemption went away, getting it back would have been a tough fight," he says.

Delays also risked pushing the project into a new funding cycle when the next transportation bill comes up again in 2009.

"We were facing cost increases and we would have had to potentially go back to square one on the funding as well," Marin says.

Hope that a tunnel option would be pursued stemmed from the results of a two-month study by a panel commissioned to review the alternative in May. Although the panel was not asked to make a recommendation, Robert O'Neil, chairman of the Dulles Metrorail Tunnel Review Panel, touted the tunnel's benefits.

"Considering the magnitude and long-term impact of this project, and considering that the intangible benefits almost entirely favor the tunnel, it is reasonable to conclude that our findings suggest strong consideration of the tunnel alternative," O'Neil says.

The panel estimated that the tunnel option would cost nearly $250 million more than the aerial option but the tunnel section would have a life expectancy of 120 years�double that of the aerial alignment. The tunnel option would also create up to $5 million in savings on operations and maintenance, according to the report.

With efforts now focused on the aerial plan, an updated request will be submitted to the FTA to enter the final design stage, followed by a request to FTA for a Full Funding Grant Agreement. Construction of the 11.6-mi. first phase of the project could begin in late 2007 with completion in 2012. The entire project is estimated for completion in 2015.