As the parks it created finally fill with activity and the project fades from newspaper headlines, Boston’s Big Dig is subtly slipping into the city’s history.

Officially known as the Central Artery Bridge/Tunnel Project, the Big Dig buried an elevated freeway in downtown Boston and added a new freeway tunnel under Boston Harbor connecting Logan Airport to the city’s urban core.

Most of all, the project is known for its delays (over 15 years of construction) and huge price tag: over $14.6 billion, a total of roughly $22 billion with interest. The cost overruns were so severe it was responsible for temporarily cutting off the state’s Federal highway funding, dozens of lawsuits, and was even featured multiple times on NBC Nightly News’ regular feature “The Fleecing of America.”

Commonwealth politicians are content to put it the project behind them, trying to distance themselves from any involvement. Urbanists, meanwhile, are eager to point out the project’s many accomplishments. Downtown property values have increased, new parks have been created, and developers are beginning the work of re-knitting urban neighborhoods long divided by the unsightly highway. Reduced gridlock has improved urban air quality, and the harbor tunnel has improved access to the airport for transit riders (through the Silver Line) and motorists alike.

However, one unanswered question lurks in the air: could the Big Dig have cost less?

Like any historical counterfactual, a definitive answer is impossible. However, much could be revealed through a detailed case study. What delays were avoidable? What complications did the engineers overlook? Is there any evidence cost estimates were deliberately manipulated? Should the partnership between the Turnpike Authority and Bechtel/Parsons Brinkerhoff been differently designed to improve accountability? Could the project’s 144 separate construction contracts have been written differently? Were Federal highway standards or environmental laws responsible for excessive costs? In short, could changes to the underlying public policy structure have resulted in different costs and construction time? To my knowledge, these questions have not been deeply examined by scholars. If any readers are aware of studies, please post them below.

The result may not be nefarious scheming by greedy contractors. In fact, scholar Bent Flyvbjerg has argued major causes of cost overruns are systematic under-estimation of costs due to political pressure, and a failure to properly account for the inevitable risks that occur as a result of the complexity of megaprojects.

Image via Wikipedia

Far from a matter of historical interest, the high cost of transportation infrastructure is a pressing policy issue in a state currently spending $3 billion re-build bridges and planning an extension of the city’s Green Line, among other proposed projects. The high cost of transportation projects was raised recently on an email list operated by the Somerville Transportation Equity Partnership, in a thread grousing about the $600,000 price for a bike cage and high cost estimates for the Green Line extension. The issue provoked a rare response from the Commonwealth’s Secretary of Transportation Jeffrey Mullan himself, who denied the costs were inflated or the bidding process is faulty. Although the message concedes “things cost a lot; unacceptably so sometimes,” the post omits any speculation as to why.

Perhaps one day the question will be subject to the scrutiny it deserves.