The Central Artery/Tunnel Project (CA/T Project), commonly known as the Big Dig, was a megaproject in Boston that rerouted the Central Artery of Interstate 93 (I-93), the chief highway through the heart of the city, into the 1.5-mile (2.4 km) Thomas P. O'Neill Jr. Tunnel. The project also included the construction of the Ted Williams Tunnel (extending I-90 to Logan International Airport), the Leonard P. Zakim Bunker Hill Memorial Bridge over the Charles River, and the Rose Kennedy Greenway in the space vacated by the previous I-93 elevated roadway. Initially, the plan was also to include a rail connection between Boston's two major train terminals. Planning began in 1982; the construction work was carried out between 1991 and 2006; and the project concluded on December 31, 2007, when the partnership between the program manager and the Massachusetts Turnpike Authority ended.
The Big Dig was the most expensive highway project in the United States, and was plagued by cost overruns, delays, leaks, design flaws, charges of poor execution and use of substandard materials, criminal charges and arrests, and the death of one motorist. The project was originally scheduled to be completed in 1998 at an estimated cost of $2.8 billion (in 1982 dollars, US$7.4 billion adjusted for inflation ). However, the project was completed in December 2007 at a cost of over $8.08 billion (in 1982 dollars, $21.5 billion adjusted for inflation, meaning a cost overrun of about 190%) . The Boston Globe estimated that the project will ultimately cost $22 billion, including interest, and that it would not be paid off until 2038. As a result of a death, leaks, and other design flaws, Bechtel and Parsons Brinckerhoff—the consortium that oversaw the project—agreed to pay $407 million in restitution and several smaller companies agreed to pay a combined sum of approximately $51 million.
The Rose Fitzgerald Kennedy Greenway is a roughly series of parks and public spaces which were the final part of the Big Dig after Interstate 93 was put underground. The Greenway was named in honor of Kennedy family matriarch Rose Fitzgerald Kennedy, and was officially dedicated on July 26, 2004.
Origin
This project was developed in response to traffic congestion on Boston's historically tangled streets which were laid out centuries before the advent of the automobile. As early as 1930 the city's Planning Board recommended a raised express highway running north–south through the downtown district in order to draw through traffic off the city streets. Commissioner of Public Works William Callahan promoted plans for the Central Artery, an elevated expressway which eventually was constructed between the downtown area and the waterfront. Governor John Volpe interceded in the 1950s to change the design of the last section of the Central Artery, putting it underground through the Dewey Square Tunnel. While traffic moved somewhat better, the other problems remained. There was chronic congestion on the Central Artery (I-93), the elevated six-lane highway through the center of downtown Boston, which was, in the words of Pete Sigmund, "like a funnel full of slowly-moving, or stopped, cars (and swearing motorists)." In 1959, the 1.5-mile-long (2.4 km) road section carried approximately 75,000 vehicles a day, but by the 1990s, this had grown to 190,000 vehicles a day. Traffic jams of 16 hours were predicted for 2010.
The expressway had tight turns, an excessive number of entrances and exits, entrance ramps without merge lanes, and as the decades passed and other planned expressways were cancelled, continually escalating vehicular traffic that was well beyond its design capacity. Local businesses again wanted relief, city leaders sought a reuniting of the waterfront with the city, and nearby residents desired removal of the matte green-painted elevated road which mayor Thomas Menino called Boston's "other Green Monster" (as an unfavorable comparison to Fenway Park's famed left-field wall). MIT engineers Bill Reynolds and (eventual state Secretary of Transportation) Frederick P. Salvucci envisioned moving the whole expressway underground.