Big Dig is the unofficial name of the Central Artery/Tunnel Project (CA/T), a megaproject that rerouted the Central Artery (Interstate 93), the chief controlled-access highway through the heart of Boston, Massachusetts, into a 3.5 mile (5.6km) tunnel under the city. The project also included the construction of the Ted Williams Tunnel (extending Interstate 90 to Logan International Airport), the Zakim Bunker Hill 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. The project concluded on December 31, 2007, when the partnership between contractor Bechtel/Parsons Brinckerhoff and the Massachusetts Turnpike Authority ended.
