A $71 billion behemoth of a regional transit project could solve the commuting problems your children might face three decades from now.

It's called the Trans Regional-Express or T-Rex for short. The Regional Plan Association, calls it the "largest public works project undertaken since the early 20th Century."

T-Rex is a massive commuter rail system expansion of existing NJ Transit, Long Island Railroad and Metro North lines to meet a projected 34 percent increase in suburban commuters to Manhattan by 2040. The RPA outlined the T-Rex when its Fourth Regional Plan was released in November and provided a detailed plan on Wednesday.

Could T-Rex save a region choking on its own congestion or will it go extinct on the heap of grand plans never built?

T-Rex proposes building more Hudson River and East River rail tunnels, creating two new subterranean rail lines under Manhattan and rehabbing long dormant rail lines in New Jersey. It would require New York and New Jersey's transit agencies to cooperate, so trains from any agency could run through Manhattan across the region.

"It's leveraging the commuter rail system and using it to augment and relieve congestion on transit systems, and to create express service," said Richard Barone, RPA vice president of transportation. "We see it as a multi-decade investment, that keeps going. We are digging ourselves out of a hole."

RPA wants to lure commuters onto T-Rex trains by promising faster travel from Paterson to Columbus Circle in 26 minutes, to Grand Central Terminal in 29 minutes, or from North Bergen to midtown in 11 minutes.

IOW have a rail transit regime that works as reliable intra-state transportation instead of a bunch of diesel-wasting trains doing nothing all day in Sunnyside Yards — SiriusXM Rob Thomas Radio (@InsiderTwets) April 13, 2018

Similar plans have been done in Paris and in London, where the first phase of the 15 billion pound Cross rail project was built in nine years and is about to go into service.

The first phase of T-Rex relies on the entire $30 billion Gateway project, Barone said. Gateway would construct two new Hudson River rail tunnels, replace and build a second Portal Bridge over the Hackensack River, construct a second set of Northeast Corridor tracks from the tunnel to Newark, a loop track at Secaucus for Bergen County trains to access the NEC and an addition to Penn Station New York.

T-Rex would push the new Gateway tunnels across Manhattan across the East River and build a rail station at 31st Street and Third avenue that would connect at a station with the proposed a proposed north-south Manhattan spine.

The second phase builds that spine or "the backbone" of T-Rex, a underground rail line along Third Avenue, connecting "the Bronx to the Battery." The uptown-downtown spine would connect to the extended commuter line crossing Manhattan at 31st Street and Third Avenue.

Two new subterranean crosstown lines would bisect Manhattan at 57th and Houston streets and cross the Hudson to New Jersey. The 57th Street line would connect to the Long Island Railroad's Eastside Access line to Queens and to a West Shore rail line in Bergen County.

The Houston Street line would enter New Jersey in Hoboken and use the dormant Bergen Arches rail line through the Palisades to connect with NJ Transit lines. Both would connect to the Manhattan spine.

Those tunnels built would allow for creation of the "Jersey Loop" to take pressure off the PATH, the New York subway system and the Port Authority bus terminal.

T-Rex could build New Jersey projects that have been shelved for years. That includes the Monmouth-Ocean-Middlesex line along Route 9 to Ocean County, a Paterson-Newark Light rail line, and the reactivation of passenger service on the New York, Susquehanna and Western Railroad line to Paterson and the former West Shore line.

Running trains through the region will also require standardizing trains, electric systems, stations, fares and scheduling between NJ Transit and the MTA's commuter lines. While a complete merger is unlikely, the railroads could be operated by an existing regional agency, Barone said.

To finance it, RPA proposes that $2.4 billion annual nibbles are taken out of the $71.4 billion cost over 30 years, Barone said. The two states will have to come up with funding, but T-Rex can be financed with a mix of government and private funding, similar to Cross Rail he said.

T-Rex also will use ideas RPA has proposed to reduce projects costs which could knock $20 billion off the estimated cost, Barone said.

Experts questioned why the plan doesn't use subways and rapid transit.

"Rapid transit is the answer, not commuter rail," said James C. Greller, a retired NJ Transit and NJDOT planner. "I don't see the ridership warranting this expenditure."

Alternatives have been overlooked, such as extending L train and 7 line subway tunnels to New Jersey, experts said.

"If they extend the L to Hoboken, they will have their direct connection to the subway by going one more station under river and connecting to Hudson Bergen Light rail, NJ Transit commuter trains and relieve pressure on the PATH," Greller said.

The plan also is silent about extending the 7 line subway to New Jersey which is supported by the New Jersey Association of Railroad Passengers, said Len Resto, NJ-ARP president.

"That is a project that can be "near-term" and offers significant capacity gains," Resto said. "Instead, it is relegated to a mention at the end of one paragraph. Opportunity missed."

Resto said T-Rex also says nothing about the role of self-driving vehicles, the affect of climate change on transit facilities or preserving abandoned rail lines from development.

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

