FORMER MASSACHUSETTS GOVERNORS Michael Dukakis and William Weld made one more push for state officials to revisit their $12 billion cost estimates for a connector tunnel between South and North stations and reassess the feasibility of digging under Boston streets once again without the fear of repeating Big Dig history.

“This study is preposterous,” Dukakis said at the joint meeting of the Department of Transportation board of directors and the MBTA’s Fiscal and Management Control Board meeting Monday. “How can the North South Rail Link cost what it’s costing to do the London rail link?… I’m concerned this is just an excuse for another reason for delay on a project that is absolutely essential.

Dukakis said the link is not just about closing the “mile separation” between North and South stations but easing traffic on the state’s choked highways as well. The 85-year-old transit aficionado said he and his wife Kitty recently left their Brookline home to speak to the “lifers group” at MCI-Norfolk. He said they left for the 19-mile trip at 4:30 and didn’t arrive until two hours later because of traffic, which he said would be lessened by a “first class regional rail system.”

Weld said the tunnel is not just about ease of travel, with the investment going toward boosting the economy

“It goes beyond transportation,” he told the board. “I think of it in large measure as a workforce issue as well. If you live south of town as I now do, it’s hard to get north of town. As long as you have to stop at South Station and can’t get to North Station, some jobs northwest and north of Boston are out of reach for people south of Boston and they may be the best qualified for those jobs.”

Barry Bluestone, founding director of the Dukakis Center for Urban and Regional Planning at Northeastern University where Transportation Secretary Stephanie Pollack once served as assistant director, said the feasibility study had major flaws in its conclusions. He said an analysis of demographics shows a “bifurcated labor market” between north and south.

“If you live, north of the city, 85 percent of the people work north of the city, and the same trend shows in the south as well,” he said.

Braintree Mayor Joseph Sullivan, a member of the transportation board, said state officials are understandably skittish, suffering from what he called the “Big Dig hangover.” He suggested looking at some alternative forms of funding, such as asking businesses who would benefit to contribute to an enterprise fund the way some companies along the Green Line Extension have done. But he said a North-South link would send a message that state officials understand there is value beyond Boston.

“There will be benefits to linking this (one) mile separation,” he said. “We’ve got to be careful about being city-centric all the time.”

Scott Hamwey, the project’s director, submitted a summary letter to the fiscal board about comments received on reopening the feasibility study with many of the submissions criticizing the cost. Hamwey’s letter defended the estimate, claiming many of the commenters were merely attacking the figure without support.

“Many of these (criticisms) lacked any supporting evidence for their claims of mis-estimation,” Hamwey wrote. He said next month’s meeting of the board will focus on explaining the costs in more detail and address questions and criticisms.

Dukakis said the board should move forward quickly, especially with Democrats about to take control of the House of Representatives. He noted the expected chair of the transportation committee, US Rep. Peter DeFazio of Oregon, is a Needham native and intimated he would be a friendly ear for requests from the Bay State.

“We’ll find you a sponsor, don’t you worry about it,” he told the board. “I apologize if I sound impatient but I am impatient. As you get to be 85, you’ve got to kind of confront your mortality a little bit.”