Boston Central Artery/Tunnel Project, Massachusetts

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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.

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