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The Central Artery/Tunnel Project - The Big Dig
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The Big Dig

Recognized as the largest, most complex, and technologically challenging highway project in the history of the United States, the Central Artery/Tunnel Project significantly reduced traffic congestion and improved mobility in one of America's oldest and most congested major cities. In addition, it helped improve the environment, and established the groundwork for continued economic growth for Massachusetts and all of New England.

The Project replaced Boston's deteriorating six-lane elevated Central Artery (I-93) with an eight-to-ten lane state-of-the-art underground highway, two new bridges over the Charles River, extended I-90 to Boston's Logan International Airport, and Route 1A, created more than 300 acres of open land and reconnected downtown Boston to the waterfront.

When planning for the CA/T Project began with the preparation of environmental impact documents in 1982, transportation experts could not accurately predict the challenges that lay ahead on the long journey to design and construction. Congress approved federal funding and the Project's basic scope in April 1987.

Construction began in September 1991 on a Bypass Road through South Boston to take truck traffic off neighborhood streets and on the third tunnel to cross Boston Harbor. The first major milestone, the opening of the tunnel - dedicated and named after baseball legend Ted Williams. Substantial completion was reached January 13, 2006. Three major milestones opening were reached in 2003.

Central Artery/Tunnel Project Milestones

1982: Work begins on Final Environmental Impact Statement/Report (FEIS/R)
1985: Final Environmental Impact Statement/Report (FEIS/R) filed and approved early the next year.
1986: Bechtel/Parsons Brinckerhoff begins work as management consultant.
1987: Congress approves funding and scope of Project.
Building acquisition and business relocation process begins (no private homes taken).
1988: Final design process under way.
Exploratory archaeology digs begin.
1989: Preliminary/final design and environmental review continue.
1990: Congress allocates $755 million to project.
1991: Federal Highway Administration issues Record of Decision, the construction go-ahead. Final Supplemental Environmental Impact Statement/Report (FSEIS/R) approved. Construction contracts begin to be advertised and awarded.
Construction begins on Ted Williams Tunnel and South Boston Haul Road.
1992: More than $1 billion in design and construction contracts under way.
Dredging and blasting for the Ted Williams Tunnel ongoing.
Downtown utility relocation to clear path for Central Artery tunnel construction begins.
Archaeologists find 17th and 18th century artifacts at a North End dig.
1993: South Boston Haul Road opens.
All 12 tube sections for Ted Williams Tunnel are placed and connected on harbor floor.
1994: Charles River Crossing revised design and related FSEIS/R approved.
New set of loop ramps open in Charlestown.
1995: Ted Williams Tunnel opens to commercial traffic.
1996: Downtown slurry work under way for I-93 tunnels.
1997: Overall utility work 80 percent complete.
1998: Enter peak construction years.
Construction begins on the Charles River Crossing.
1999: Overall construction 50 percent complete.
New Broadway Bridge opens.
Leverett Circle Connector Bridge opens.
2000: Nearly 5,000 workers employed on the Big Dig
2001: Overall construction 70 percent complete.
2002: Leonard P. Zakim Bunker Hill Bridge completed.
2003: I-90 Connector from South Boston to Rt. 1A in East Boston opens in January.
I-93 Northbound opens in March.
I-93 Southbound opens in December.
2004: Dismantling of the elevated Central Artery (I-93).

Opening of the tunnel from Storrow Drive to Leverett Circle Connector, which provides access to I-93 North and Tobin Bridge.
2005: Full opening of I-93 South.

The opening of the completely renovated Dewey Square Tunnel, including new exit and entrance ramps.

Opening of the two cantilevered lanes on Leonard P. Zakim Bunker Hill Bridge.

Opening of permanent ramps and roadways at I-90/I-93 Interchange and in other areas.
2006: Reached substantial completion of the Central Artery/Tunnel Project in January.

Spectacle Island Park opens to the public.
2007: Restoration of Boston city streets.

Continued construction of the Rose Kennedy Greenway and other parks.

Construction on development parcels will continue after the Central Artery/Tunnel Project is finished.
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