WASHINGTON (Map, News) - Contractors for the endangered Dulles Rail extension reached an agreement Friday that will allow them to continue engineering and utility work for another month despite grave doubt over the rail's ability to receive crucial federal funds.

It's a gamble that banks on the 23-mile track's first phase receiving $900 million from the Federal Transit Administration, which the federal agency says is unlikely. The project is too expensive to justify the comparatively modest number of people who will ride it, according to the agency, which also cites disputes over management and Metro funding as reasons to withhold the funding.

Three Maryland members of Congress and D.C. delegate Eleanor Holmes Norton urged U.S. Transportation Secretary Mary Peters in a letter Wednesday to approve Dulles Rail. A source said the decision could come in the next two weeks.

But in the meantime, the airports authority has taken the risk of allowing contractors to continue work as if the project were on track.

Friday's agreement - inked with the Metropolitan Washington Airports Authority, which is managing the project - leaves open how much the cost will escalate while the FTA considers the funding.

"What we've agreed to do is sit down and evaluate any impact" to the price, said Howard Menaker, a spokesman for contractors Bechtel Infrastructure and Washington Group International.

Similar agreements have been reached since Aug. 1, when a contractual deadline passed that would have driven up the price tag by as much as $6 million a month.

Virginia Transportation Secretary Pierce Homer, who has said $140 million has been spent on Dulles Rail, on Friday said it is not known how much the state will owe the two contractors should the project fail. The commonwealth, he said, "respects contractual rights."

"The contractor has incurred liabilities and costs, nearly 200 engineers working on this project as we speak, they have leased office space ... those costs have been incurred and the contractor has to be paid for those legitimate expenses," Homer said.

The project is also funded through Dulles Toll Road revenue, some state funding and a special Fairfax County tax district.

wflook@dcexaminer.com