Yet his stiffest leadership test as governor produced mixed results.
Romney was praised, even by some Democrats, for his energetic, take-charge management style. But he also drew criticism for playing to the media and dodging personal blame.
One move he made was to blame fellow Republican Matt Amorello, chairman of the Massachusetts Turnpike Authority, an independent agency largely outside the governor's control that was overseeing the project.
Later, however, it was Romney who was faulted for not taking stronger action to fix the problem-plagued Big Dig well before the collapse.
"He was all sizzle and no steak," said former Massachusetts governor Michael Dukakis, the 1988 Democratic presidential nominee.
Romney's campaign didn't respond to requests for comment.
His administration bungled one response to the collapse by hiring Big Dig project manager Bechtel/Parsons Brinckerhoff to inspect the ceiling repairs. Bechtel oversaw construction of the tunnel, so giving it the job of judging its own work created a conflict of interest; Romney later admitted it was a mistake. Bechtel at the time was a focus of state and federal investigations into the collapse.
For that foul-up, Romney blamed his transportation secretary, prompting a sarcastic swipe in a Boston Herald editorial: "If there's glory to be gained in handling a crisis, count on Gov. Mitt Romney to show up in person to grab it. If there is blame to be swallowed, well, isn't that what subordinates are for?"
Romney, too, had ignored warnings from state Sen. Marc Pacheco, chairman of a legislative oversight panel, that Bechtel officials were too cozy with turnpike authority officials overseeing the project. Pacheco had urged Romney to suspend Bechtel. Federal investigators later found that the lack of a tunnel inspection program contributed to the fatal accident.
"It was essentially the proverbial fox guarding the chickens," said Pacheco, a Democrat. "It continued under Romney's watch."
The $15 billion Big Dig replaced an elevated highway that ran through Boston with a series of tunnels, ramps and bridges. The project was plagued for two decades by mismanagement, design flaws, cost overruns, leaks, falling debris and other problems linked to faulty construction.
The accident was a prime opportunity for former businessman Romney to showcase his management skills. He was facing criticism for ignoring the state's needs with his growing schedule of out-of-state travels as he prepped for an expected White House run in 2008.
Romney wasn't shy about stepping before the TV cameras to reassure a jittery public. He prowled the cavernous Big Dig tunnels flanked by engineers and investigators. At times he sounded more like an engineer than a politician as he explained details of the collapse in televised news conferences.
It was a chance to burnish his credentials as a turnaround artist. As a venture capitalist, Mitt Romney retooled struggling companies and made a fortune. In Salt Lake City, he turned around the scandal-plagued 2002 Winter Olympics and used the experience as a springboard to the Massachusetts governorship.
Days after the collapse, Romney persuaded the Democratic-controlled Legislature to approve emergency legislation giving him the power to oversee inspections and final authority on reopening the tunnels. He also ordered a "stem to stern" review of the project.
"His leadership was impressive," said former state Sen. Steven Baddour, a Democrat who was co-chair of the Joint Committee on Transportation. "You could criticize him on the issues. But when it comes to the management of a crisis, that's his wheelhouse."
Baddour recalled being summoned to a briefing in Romney's office shortly after the accident. He expected to find a room crowded with engineers and other officials. Instead he was alone with Romney, whose grasp of the accident and engineering details impressed Baddour.
Romney's prime target was Amorello, whom he had long accused of mismanaging the turnpike authority and the Big Dig.
Romney had previously tried to force Amorello out, but was rebuffed in court. Amorello was finally ousted after the tragedy, with pressure from Romney and others intensifying.
"I thought Romney scapegoated Amorello because it was politically convenient," said Warren Tolman, a former Democratic state senator.
Tolman said Romney should have been more aggressive before the accident to take control of the Big Dig from Amorello and the turnpike authority.
"He looked great on TV, but he didn't do the dirty work of what needed to be done," said Tolman.
Romney never lobbied state lawmakers as hard on the Big Dig as he did on his health care overhaul plan, a cornerstone of his presidential ambitions, Tolman said.
"He didn't try to roll the boulder up the hill on the Big Dig," said Tolman.
Asked by reporters why he had not moved sooner to take control of the Big Dig, Romney blamed the Legislature for blocking him.
In a 2007 report, the National Transportation Safety Board criticized the MassachusettsTurnpike Authority, designers, inspectors and many of the contractors involved in the Big Dig.
The board said the collapse could have been avoided if designers and construction contractors had considered that the epoxy glue holding support anchors for the ceiling panels could slowly pull away. The NTSB said the turnpike authority contributed to the accident by failing to put in place a timely tunnel inspection program.
Bechtel/Parsons Brinckerhoff in 2008 agreed to pay more than $400 million to settle a lawsuit the state filed over the collapse.