Concept
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) tunnel named the 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 7.4 billion adjusted for inflation ). However, the project was completed in December 2007 at a cost of over 21.5 billion adjusted for inflation, meaning a cost overrun of about 190%) . The Boston Globe estimated that the project will ultimately cost 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.
