Gateway, the $23.9 billion project to overhaul century-old rail infrastructure in and around New York City, has commitments for preliminary work and oversight. The Port Authority of New York and New Jersey pledged $35 million for engineering studies for a Hudson River tunnel, matching an amount promised by national rail operator Amtrak, subject to their boards’ approval, according to a Port Authority news release. They also have agreed with the U.S. Transportation Department and commuter agency New Jersey Transit to form an executive committee, necessary to secure grants. Gateway, which includes the replacement of a breakdown-prone swing bridge in the New Jersey Meadowlands and the addition of high-speed track, has yet to acquire full funding, and wouldn’t be complete until 2030. For the tunnel portion, though, U.S. Transportation Secretary Anthony Foxx has agreed to seek expedited environmental reviews and permitting. The pair of 106-year-old tubes are key for 105,000 New Jersey Transit rail passengers who commute to Manhattan on weekdays, and for travelers on Amtrak’s Northeast Corridor line, the nation’s busiest, which runs between Boston and Washington. Each must be closed for at least a year for an overhaul, and is subject to constant monitoring and maintenance of copper cable and concrete lining after damage by Hurricane Sandy floodwaters in 2012. They will be out of service in less than 20 years, according to Joseph Boardman, chief executive officer of Amtrak. “That’s what I’m focusing a lot on, to speed the timeline because of the urgency,” U.S. Senator Cory Booker, a New Jersey Democrat, said by telephone. “Anthony Foxx is a hero in this.”