Fifteen Democratic senators admonished the Trump administration for the sluggish progress on a new rail tunnel between New York and New Jersey, centerpiece of the so-called Gateway program of major infrastructure projects in the critical transit artery.

In a letter Thursday, the Democrats, from eight states along the Northeast corridor, urged Federal Railroad Administration Administrator Ronald Batory to say when the department will complete an environmental review needed to advance the new Hudson River tunnel, estimated to cost $11.3 billion. They said Batory had not provided additional timing details since a July Senate hearing when he said it could take another year to complete the remaining steps of the review.

“Further delays risk the shutdown off one or both of the existing 110-year-old tunnels—which would be devastating to our constituents, threaten public safety, and cause potentially irreversible damage to our regional and national economies,” said the senators, including Minority Leader Chuck Schumer of New York, Richard Blumenthal of Connecticut and Elizabeth Warren of Massachusetts.

The call for progress is the latest flareup in the long-running battle over the program to overhaul rail and bridge infrastructure connecting New York and New Jersey. The Trump administration has said those states are responsible for both the funding and delays of the multibillion-dollar project, while critics have accused the Trump administration of slow-walking the improvements, which most directly serve constituents in Democratic strongholds.

The rail link beneath the Hudson River is critical for commuters on New Jersey Transit and Amtrak’s Northeast Corridor, the busiest and most profitable U.S. route with more than 800,000 daily passengers. It sustained severe structural and electrical-system damage from Hurricane Sandy in 2012.

The Senators noted the corridor also has national importance, citing a 2019 report that estimated closing one of the tunnel’s two rail tubes would shave some $16 billion from the U.S. economy.

Representatives for the Transportation Department and FRA didn’t immediately respond to an email seeking comment.

A catenary-wire failure just outside the tunnel at New York Penn Station interrupted service between New Jersey and Manhattan on Feb. 3, stranding or inconveniencing tens of thousands of commuters for eight hours.

In a Feb. 4 statement, Amtrak spokesman Jason Abrams said the incident “illustrates why we need to build Gateway—as if we had a second tunnel (with two additional tracks), trains could maneuver around the problem and minimize the impact/severity of delays.”