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Project Profile: Boston Central Artery/Tunnel Project, Massachusetts

Narrow state highways in eight Oklahoma counties are to be  repaved and widened under a $41.5 million loan of federal funds to the state  highway department

The Central Artery/Tunnel Project opened three major highway tunnels and an innovative river crossing. The reconstruction of I-93 through downtown Boston.
Source: Credit to Massachusetts Turnpike Authority

Project Name

Boston Central Artery/Tunnel Project


Boston, Massachusetts

Project Sponsor / Borrower

Massachusetts Turnpike Authority

Program Areas

Alternative Project DeliveryProject Finance Tolling and PricingTIFIA

Value Capture Techniques

Value Capture: Reconnecting Communities with Highway Capping Park and Leveraging Private Sector Investments. There was a missed opportunity with value capture – private landowners and developers with property bordering what is now The Greenway have benefitted from a big windfall as the value of their land has shot up. The project has proven successful as a public space and catalyst for development including attracted over $7 billion in private investment, adding more than 43,000 jobs along the I-93 corridor and in the South Boston Seaport District


Highway, Tunnel, and Bridge


The project built a framework for future growth in the city and New England in general. The Boston, Massachusetts had a world-class traffic problem called the Central Artery. The Central Artery was an elevated highway running through the center of downtown. When it opened in 1959, the Central Artery carried about 75,000 vehicles a day. In the early 1990s it carried upwards of 200,000 making it one of the most congested highways in the United States. The accident rate on the Central Artery was four times the national average. The two tunnels between downtown Boston and East Boston/Logan Airport had the same issue. Without major improvements, Boston expected a traffic jam for up to 16 hours a day by 2010. The annual cost to motorists from this congestion was an estimated $500 million. Costs included a high accident rate, wasted fuel from traffic, and late deliveries. The elevated highway displaced 20,000 residents. It also cut off the North End and Waterfront neighborhoods from downtown. This limited these areas' ability to take part in the city's economic life.

The Boston’s Big Dig project replaced the elevated deteriorating six-lane elevated Central Artery (I-93) with an underground expressway beneath the existing road, extended the I-90 tollway underground to the South Boston Seaport and Logan International Airport, built a new 10-lane bridge over the Charles River, and built a new 4-lane tunnel under Boston's harbor and ship channel. A new underground transit line (Silver Line) was also built as part of a package of transportation improvements. By removing the elevated highway, the project created more than 300 acres of open land while reconnecting downtown Boston to the waterfront and spur economic development. The project has been called the largest, most challenging highway project in U.S. history.


$ 14.8 billion

Funding Sources
  • Federal aid: $7 billion
  • State bonds: $7.8 billion – to be paid back by tolls, as well as State and Federal taxes
Project Delivery / Contract Method


Private Partner

The Central Artery/Tunnel Project was first owned and managed by the Massachusetts Highway Department. It was then run by the Massachusetts Turnpike Authority (MTA) and was part of the Metropolitan Highway System (MHS). Bechtel/Parsons Brinckerhoff (B/PB) provided design and construction management consulting. This is a joint venture of Bechtel Corporation of San Francisco and Parsons Brinckerhoff Quade & Douglas, Inc., of New York.

Project Advisors / Consultants

Design and construction management consultants: Bechtel Corporation and Parsons Brinckerhoff



Duration / Status

Construction occurred from 1991 to 2007. The project conceived (1985), planned, designed, and constructed over a period of 25 years, from 1982 through 2007.

Financial Status / Financial Performance

Bonds to be paid in full by 2038

  • The project built a series of parks with water features and other amenities in the path of the old elevated Central Artery. This space is now known as the Rose Kennedy Greenway.
  • The Leonard P. Zakim Bunker Hill Memorial Bridge, built as part of the project, is one of the widest cable-stayed bridges in the world.
  • Reconnected neighborhoods cut off the Financial District from the waterfront historic North End Neighborhood by the old highway. Enhanced urban design and quality of life in areas that had been cut off or overshadowed by the elevated highway structure.
  • Created more than 45 parks and major public plazas including 100-acre Spectacle Island's park and pathways.
  • Relieving Congestion to Boost Economic Competitiveness. Reduced traffic and improved mobility in one of America's oldest, most congested major cities and produced a 12 percent reduction in citywide carbon monoxide levels. Residents' average travel times from the I-90/I-93 interchange to Logan Airport during peak periods have dropped from 42 to 74 percent.
  • Installed about 5,000 miles of fiber optic cable and 200,000 miles of copper telephone cable.
  • At its peak, the Big Dig employed more than 5,000 workers in a range of construction jobs, all earning a salary and improving their skills. This was part of the project’s social value for Bostonians, beyond the obvious practical element of gaining new highways.
  • Transformed the city and the region in less than 10 years, CA/T has spurred billions in new economic development, including millions of sq ft of new construction and green space in the heart of the city.
  • Deployed the biggest, first, and most innovative uses of slurry-wall technology, immersed-tube tunneling and tunnel jacking.
  • The project attracted $7 billion in private investment, adding more than 43,000 jobs along the I-93 corridor and in the South Boston Seaport District, 7,700 new housing units with 1,000 affordable housing units, 10 million square feet of office and retail space, and 2,600 hotel rooms.
Related Links / Articles

Jonathan Gulliver – Massachusetts Highway Administrator
(857) 368-4636

Interstate 93 tunnel in Boston, part of the Central Artery/Big  Dig Project

Interstate 93 tunnel in Boston, part of the Central Artery/Big Dig Project
Source: Credit to Rene Schwietzke


Boston, showing The Greenway (45 parks and  major public plazas) running through the middle of City of Boston.

Aerial photo of Boston, showing The Greenway (45 parks and major public plazas) running through the middle of City of Boston.
Source: Credit to the Massachusetts Department of Transportation

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