U.S. Rep. Frank Wolf is asking for an independent audit of the Dulles Rail project to prevent Big Dig-type price tag escalation and “ensure the project is built at the lowest cost possible.” The Virginia Republican wrote a letter on Tuesday to the Metropolitan Washington Airports Authority, which is building the 23-mile rail line connecting the Metro system to Washington Dulles International Airport and beyond.

He said the project needs an independent set of eyes. If the authority doesn’t add one, he said he would ask the U.S. Department of Transportation’s inspector general to step in.