People in Boston are talking about the Big Dig.  Many of them have been inconvenienced by the closing of one portion of the extensive tunnel system, which occurred after several concrete roof panels fell on a car at 11 P.M. on July 10, killing a woman on her way to the airport (but miraculously sparing her husband, the driver). Others, including the economists who have been trooping in and out of town, are aware of the embarrassment it has caused the city around the world.

What's the real story?  Here are four sets of facts to keep in mind.

1. It's an election year. Gov. Mitt Romney, who has acquired responsibility to sign off on the completed project, is running for Republican presidential nomination. Attorney General Thomas Reilly is running for governor.  Romney, a venture capitalist who made his political reputation rescuing the 2002 Salt Lake City Olympics from a bribery scandal, has every incentive to make the Big Dig situation seem as bad as possible. So does Reilly, a veteran prosecutor. Trailing in his race, he is concentrating on criminalizing the case.

2. The newspapers are candidates, too. The tabloid Boston Herald, with fresh hopes to remain afloat (having recently divested itself of a string of suburban papers), waded into the story with gusto. The formerly-establishmentarian Boston Globe, having been sold to New Yorkers in the Ô90s, has been campaigning against the Big Dig for five years, ever since the out-of-towners took control. Both papers have sprouted the little standing headlines on their stories ("The Mistakes," "The Outrage," etc., etc., in the one case; "Big Dig, Big Trouble" in the other) that signify dreams of a Pulitzer Prize.

3. The project has been an exercise in political economy, or economic politics, since the beginning. Conceived at a time when Richard Nixon was president by a young civil engineer/reformer named Frederick Salvucci as an alternative to highway expansion that then was threatening Boston, the project was taken up in 1974 by the first administration of Gov. Michael S. Dukakis (Salvucci became Dukakis' Secretary of Transportation). It was sold to Congress a dozen years later by House Speaker Thomas P. (Tip) O'Neill (D-Mass.). Gov. William Weld took it over and improved it when he replaced Dukakis in 1990 (the beautiful Christian Menn bridge was chosen by Weld's transportation secretary, Richard Taylor). Peter Zuk managed the project through the tumult of the Gingrich Revolution; he slipped out the back door a year after the state introduced "integrated project management," diluting contractor Bechtel/Parsons Brinckerhoff's legal accountability. (Zuk is now rebuilding the London Underground).James Kerasiotes single-mindedly oversaw the Dig until 2000, when he was fired for failing to report overruns in a timely fashion. Former Republican state senator Matthew Amorello, appointed by acting-Gov. Jane Swift (who replaced Weld's successor, Gov. Paul Cellucci), had responsibility for the Dig after 2002 -- until earlier this month emergency legislation gave oversight to Gov. Romney.

4. Despite the expense, the Big Dig is a considerable success. Its cost escalated from a low-ball initial appropriation of $2.5 billion in O'Neill's time to an eventual cost of more than $15 billion, thanks in large part to budgetary gamesmanship, especially after control of the U.S. House of Representatives passed from the Democrats to the Republicans. Ever-mounting pressure to trim expenses in recent years led to ineffective oversight, shoddy workmanship in some details and lackadaisical inspection protocols -- a kind of failure of fiscal nerve that now has translated into a tragic death.  Amenities such as the 27-acre "greenway" park that is to replace the unsightly old elevated highway are suffering as well. But the fact is that the Dig itself has delivered on its original promise to a remarkable extent, easing the east-west and north-south flow of traffic through the city, removing a steel scar bisecting its heart, extending its rail network, creating a major new business district, preserving vibrant old neighborhoods from destruction. The old elevated highway had to be replaced one way or another in any event; given the complexity of the challenge, Boston did about as well as it could.

Fixing the ceiling of the Interstate 90 Connector is a relatively simple matter. Gov. Romney and Bechtel can be expected to agree in fairly short order to re-open the closed section of the road (a couple of months, they say.) Much more complicated is the kind of arms-length audit necessary to restore confidence in the mammoth project (and in arrangements for its management going forward). US Rep. Michael Capuano had proposed that the main review be conducted by the National Transportation Safety Board. Safety is its business, after all, and it has no prior involvement in the project. The system designer Salvucci has endorsed the suggestion.

Until then, many of us will reserve judgment on the quality of the construction. Meanwhile, the chapter on the Big Dig in historian Thomas Hughes' Rescuing Prometheus:  Four Monumental Projects That Changed the Modern World, published in 1998 (and available here on the Web), remains the best introduction to a landmark project that is a key to understanding the evolving politics of our times. In a century that seems likely to be dominated by adjusting to the consequences of climate change, there will be many more such large-scale undertakings, not fewer of them.  Boston's Big Dig shows how successful such megaprojects can be when then are intelligently planned -- and, alas, how essential is their careful management.