New York-bound rail commuters would pay a per-trip surcharge to finance the state's share of construction costs for new $12.9 billion Hudson River rail tunnels under a plan by NJ Transit.

A Wednesday letter from NJ Transit to the federal Department of Transportation outlines the plan, under which city rail commuters would pay a 90 cent per-trip surcharge to fund the tunnel project starting in 2020.

The surcharge would jump to $1.70 in 2028, and to $2.20 in 2038.

The fee would generate $1.9 billion for NJ Transit's share of the project, according to the letter.

New York would provide $1.75 billion, but would not hit its riders with a surcharge. Instead, the state's share would be financed with a Federal Railroad Rehabilitation and Improvement loan that New York would repay over 35 years.

The Port Authority committed $2.7 billion toward the Gateway project, which includes the tunnels, in a 10-year capital plan adopted earlier this year.

The financing plan was announced by New Jersey Gov. Chris Christie and New York Gov. Andrew Cuomo in a statement Thursday that detailed how the states will meet a commitment to fund 50 percent of the Gateway cost.

The remaining 50 percent would be funded by the federal government. A federal spending bill approved in September included only $900 million toward the project.

The new tunnels would allow repair of 107-year-old tunnels that were damaged by flood waters driven by Hurricane Sandy, which prompted Amtrak officials to warn that a tunnel could be taken out of service for a year to repair the damage, leading to a commuting nightmare. The project also funds rehabilitation of each of the old tunnels.

Gov.-elect Phil Murphy -- who succeeds Christie on Jan. 16 -- said he was happy about progress on the Gateway project, but he criticized the commuter surcharge plan.

"I'd like to know if there were alternatives that did not involve further fare hikes and, if so, why they were not pursued?" Murphy said at a public appearance in Easy Brunswick. "Once I am sworn in, we'll review the application and see if there is any way to provide additional relief for commuters and if there is, we will pursue it."

Other Democrats also slammed the agreement. State Sen. Robert Gordon, D-Bergen, called it a "travesty."

"Why is Christie agreeing to have New Jersey pay $1.9 billion when New York is only paying $1.75 billion?" Gordon asked in a statement. "What Christie is proposing to do is to commit the state to a 35-year fare hike on NJ Transit rail commuters to Manhattan on his way out the door. He should leave that decision up to the new governor and Legislature that will be sworn in next month."

NJ Advance Media staff writers Matt Arco and Brent Johnson contributed to this report.

Larry Higgs may be reached at lhiggs@njadvancemedia.com. Follow him on Twitter @commutinglarry. Find NJ.com on Facebook.