The U.S. Department of Transportation has abruptly backed out of a group that's planning to build a new train tunnel between New York and New Jersey.

The Gateway project, as it's known, is estimated to cost $24 billion, and would likely require significant federal funding. But the DOT recently withdrew itself from the board that's supervising the project, in a move it says will preserve the agency's independence as it considers a multi-billion-dollar funding request.

John Porcari, the interim executive director of the Gateway Program Development Corporation, says this is arguably the most urgent infrastructure project in the United States. The existing two-track tunnel under the Hudson River was badly damaged by Sandy, and if just one of those tracks needs to be shut down for repairs, train traffic in and out of Penn Station will be cut by 75 percent.

Porcari spoke with WNYC's Richard Hake about where the project stands, and what could happen to the region's transportation system if another Sandy-like storm hits.