The right Hudson tunnel

Albeit on wrong-headed political grounds, the Trump administration has thrown deserved cold water on Amtrak’s exorbitant Hudson River rail tunnel project called Gateway. The region badly needs a new train tunnel in order to repair those damaged by Superstorm Sandy and increase commuter capacity between New Jersey and New York. But Trump will have none of it, even reneging on a deal that the Obama administration made to cover 50% of the costs. A new tube yes, but not the overly big Gateway. The two states must now get serious about a cut-down version. Goodbye, $30 billion extravaganza that would tear down a chunk of Midtown; hello, a tube costing only — yes, only — $11 billion.

If Cuomo and his new partner across the river, Jersey’s Phil Murphy, know what’s good for them, they’ll get back to the drawing board right quick.

The feds must then make good on the 50-50 funding split they agreed to under the Obama. That’s a fair way to pay for a plan that is the nation’s most important infrastructure project. Hogwash to the Trump claim that because most riders are commuters, this is a mere “local project.” It is Amtrak’s most critical chokepoint in the country.

But what needs to change is the scope and scale. Under its current delusion, Amtrak envisions clearing more than a full city block between 7th and 8th Aves. to build a new terminal, Penn South. It puts the tag for that piece at $6 billion, a price that will certainly climb by billions more.

Current Penn Station should instead be optimized by extending the platforms to hold longer trains — making full use of the Farley Post Office, already being converted, at a cost of many millions, to Moynihan Station.

There’s also savings to be had in a simpler bridge over the Hackensack River. Amtrak wants a pair of 55-foot-high super spans with two tracks each. Why? The old two-track bridge stands at 23 feet. Save billions with a single new, mid-height bridge with four tracks.

Get the essential parts done without waste. God knows even sane infrastructure plans cost way too much in this city.