Now that U.S. Transportation Secretary Elaine Chao secretly toured the ancient, crumbling Hudson River train tunnels used by thousands of NJ Transit and Amtrak commuters daily, two U.S. Senators want her to fund and cut red tape to build new tunnels.

U.S. Senators Cory Booker and Robert Menendez, D-N.J., also invited Chao in a letter sent Wednesday to talk to commuters who are “impacted each week by countless delays to understand the urgency of moving the Gateway Tunnel project ahead by committing federal funding."

Last month, Politico reported that Chao took a secret ride through the Hudson River tunnels in April 2018, without telling the region’s four Democratic senators who had invited her in 2017 on a tour with them. The tour was part of a broader Amtrak train ride of the Northeast Corridor, an Amtrak official told Politico.

A copy of the Booker-Menendez letter sent to Chao on Nov. 6 was obtained by NJ Advance Media. It renews requests to approve applications for federal grants to fund a portion of the Gateway Tunnel project. It has been mired in political back and forth between New Jersey and New York officials and the Trump administration since 2017.

Thanks for replying to one of your NJ7 constituents! NJT service has deteriorated markedly in the 12 years I’ve lived here. Only way to improve is to build a new #Gateway tunnel—please accelerate your efforts, and let us know what we can do to help get federal $ commitment back https://t.co/DN0aYQNHLW — Eva Weinstein (@bronxgirl120) November 5, 2019

The letter also questions why approvals that would allow tunnel design work to start have been delayed. Booker and Menendez also asked about grant applications to replace the ancient Portal Bridge that carries tracks over the Hackensack River in Kearny.

Both the tunnels and bridge are owned by by Amtrak and are part of the larger Northeast Corridor rail line between Boston and Washington D.C. Federal officials characterized Gateway as regional rather than national projects.

Five years ago, Amtrak officials warned the tunnels could be closed in the near future to repair damage by flood waters driven by Hurricane Sandy. They’re not going to collapse, but the guts of the steel tunnels, concrete walls, electric wiring, signals, track and support structure for the rails, were damaged by corrosive water.

THREAD⬇️

7 years ago today, Superstorm Sandy battered the East Coast with flooding rains and devastating storm surge. For the first time in its 100+ year history, water inundated Amtrak’s North River Tunnel, severing rail service into and out of New York City. (1/9) pic.twitter.com/pNhbaODGwa — Gateway Program News (@GatewayProgNews) October 29, 2019

If one tunnel had to be closed, train traffic would be reduced by 75% to six trains an hour, crippling the flow of commuters to and from New York and harming the nation’s gross domestic product. The New York-New Jersey region generates 20% of the country’s GDP, tunnel supporters said.

Now that the secretary’s trip was revealed, Booker and Menendez said they want to use it as a jumping off point to talk about funding two new tunnels and rehabilitating the 109-year old tubes under the Hudson.

“We would have welcomed the opportunity to join you on the tour to discuss how we could partner to advance the Gateway Project…invitations we have previously extended (in 2017) still stand,” the senators wrote.

Booker and Menendez also asked why a final decision hasn’t been made on an environmental review that was expedited and finished in March 2018. A decision on that review would allow engineering and design work on the tunnels to start.

The senators also asked Chao to justify continued low rankings for the project grant applications after the states and Amtrak cut $1.4 billion from the estimated $12 billion tunnel project. Amtrak committed an additional $1.3 billion to the tunnels.

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They also asked why grants to replace Portal Bridge were given low rankings. All that’s needed is a federal grant to match the $600 million pledged by New Jersey and Amtrak’s share of the estimated $1.2 billion construction cost. NJ Transit filed a new grant application last month reiterating the larger non-federal funding commitment.

The senators reminded Chao that “the Gateway Program is absolutely critical to public safety, the nation’s economy, and the quality of life for regional commuters.”

Officials also are investigating if an idea that saved L train riders from a total shutdown for tunnel work can be used. That plan uses a “racking system” to suspend new electric cables now located inside deteriorating concrete bench walls inside the tunnel.

But that solution won’t fix all the problems resulting from flooding in the Hudson River tunnels, such as damage from salt and chemical-laden water, officials said.

Larry Higgs may be reached at lhiggs@njadvancemedia.com. Follow him on Twitter @commutinglarry. Find NJ.com on Facebook. Have a tip? Tell us. nj.com/tips.

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