Ted Williams Tunnel in the context of "Interstate 90"

The Big Dig was a megaproject in Boston that rerouted the elevated Central Artery of Interstate 93 into the O'Neill Tunnel and built the Ted Williams Tunnel to extend Interstate 90 to Logan International Airport. Those two projects were the origin of the official name, the Central Artery/Tunnel Project (CA/T Project). The megaproject constructed the Zakim Bunker Hill Bridge over the Charles River, created the Rose Kennedy Greenway in the space vacated by the previous elevated roadway and funded more than a dozen projects to improve the region's public transportation system. Planning began in 1982 and construction was carried out between 1991 and 2006. The project concluded in December 2007.

The project's general contractor was Bechtel, with Parsons Brinckerhoff as the engineers, who worked as a consortium, both overseen by the Massachusetts Highway Department. The Big Dig was the most expensive highway project in the United States, and was plagued by cost overruns, delays, leaks, design flaws, accusations of poor execution and use of substandard materials, criminal charges and arrests, and the death of one motorist.

The Big Dig ceiling collapse occurred on July 10, 2006, when a concrete ceiling panel and debris weighing 26 short tons (52,000 lb; 24,000 kg) and measuring 20 by 40 feet (6.1 by 12.2 m) fell in Boston's Fort Point Channel Tunnel (which connects to the Ted Williams Tunnel). The panel fell on a car traveling on the two-lane ramp connecting northbound I-93 to eastbound I-90 in South Boston, killing a passenger and injuring the driver. Investigation and repair of the collapse caused a section of the Big Dig project to be closed for almost a year, causing chronic traffic backups.