Boston, Massachusetts had a world-class traffic problem, an elevated six-lane highway called the Central Artery that ran through the center of downtown. When it opened in 1959, the Central Artery comfortably 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.
Traffic crawled for more than 10 hours each day. The accident rate on the deteriorating elevated highway was four times the national average for urban Interstates. The same problem plagued the two tunnels under Boston Harbor between downtown Boston and East Boston/Logan Airport. Without major improvements to the Central Artery and the harbor crossings, Boston expected a stop-and-go traffic jam for up to 16 hours a day - every waking hour - by 2010.
The annual cost to motorists from this congestion - in terms of an elevated accident rate, wasted fuel from idling in stalled traffic, and late delivery charges - was estimated at $500 million.
And traffic wasn't the only problem the old Central Artery caused in Boston. The elevated highway (which displaced 20,000 residents when it was built) also cut off Boston's North End and Waterfront neighborhoods from the downtown, limiting these areas' ability to participate in the city's economic life.