When Mitt Romney was a candidate for Massachusetts governor, in 2002, Salt Lake City's mayor cut a television commercial endorsing him. Acknowledging that the two were of different parties, the Democratic mayor said that, judging from Mr. Romney's rescue of the scandal-ridden 2002 Olympic Winter Games, Massachusetts would get a very talented leader if it elected him.

In Governor Romney's taking charge this summer of the public-confidence crisis that followed the fatal collapse of a Big Dig tunnel, he has justified the prediction.

The Big Dig has long been a publicly known financial scandal. Moreover, it has shown some engineering problems, as when two years ago water seeped through some of its slurry walls. Yet to address these problems, Governor Romney had tried but failed to remove Matthew Amorello as chairman of the Massachusetts Turnpike Authority, overseer of the Big Dig.

On the night of July 10, when motorist Milena Del Valle was crushed to death on her way to Logan Airport, the governor was vacationing in New Hampshire. His critics were quick to point out his absence from the state, noting that this summer he had been away either on vacation or on the presidential-campaign trail. Maybe so, but in response to this disaster, he acted exactly as a governor should.

Mr. Romney asked the legislature to give him emergency powers over Turnpike Chairman Amorello to investigate the tragedy. This time, the legislature said yes. (Mr. Amorello has since resigned under pressure.)

The fatal tunnel was immediately closed, and the governor ordered a minute inspection of the entire nine-mile Big Dig system. When examination revealed similar problems in the Ted Williams Tunnel, that tunnel was also closed. A few criticized this decision as grandstanding, but it was unquestionably the correct, conservative action to take.

Governor Romney has been especially effective in explaining the reasons behind each of his decisions. Although no engineer, he quickly boned up on the Big Dig's structural details, and presented them to the public in clear nontechnical language. His articulate explanations (calling the Big Dig a "tar baby" excepted) gave Massachusetts citizens confidence both that public safety was the state's number-one priority and that the Big Dig -- nexus of New England transportation -- would again be fully functioning as soon as possible.

Through his response to this tragic state emergency, Mr. Romney has proven an exemplary executive.