The opening of the southbound lanes was a milestone marking the last stretch of major construction in Boston's Big Dig, one of the largest and most expensive public infrastructure projects in U.S. history.
Elaine Cronin of Boston was the first driver to head into the new tunnel lanes Saturday morning.
"This is really wonderful," said Cronin, who was greeted by Mayor Thomas Menino and Massachusetts Turnpike Authority chairman Matt Amorello and given a Big Dig cap and a map autographed by the two men. "It's part of history."
The old highway, the Central Artery, had been hailed as a modern "highway in the sky" when it opened in 1959. But it had been overwhelmed with more than double the number of cars it was designed to carry.
Big Dig planners hope that the new project will ease traffic problems, and city officials are planning to transform the downtown area once the Central Artery has been dismantled.
It's been a long time coming.
The project was scheduled to be completed five years ago, but now isn't expected to be fully finished until 2005. Since planning started, the cost estimate for the project has ballooned from $2.6 billion to $14.6 billion.
In January, project officials opened the first major stretch of construction, a tunnel connecting Interstate 90, the Massachusetts Turnpike, to the new Ted Williams Tunnel to Logan International Airport. The I-93 northbound lanes, running adjacent to the southbound lanes through the downtown tunnel, opened in March.
Crews worked all night to prepare the new southbound lanes for Saturday's opening, putting down stripes, adjusting road barriers, and sweeping the streets.
Officials had hoped to herald the opening with an underground concert by the Boston Pops, but critics said the concert was too glitzy for the Big Dig.
Instead, Big Dig managers opted for a brief ceremony Friday. They observed a moment of silence for four workers killed during construction.
Gov. Mitt Romney, who criticized the planned Pops concert, described the opening of the southbound lanes as a milestone but said any celebrations should wait until the project is finished, the overhead artery torn down, surface roads paved and parks planted.
"There is a light at the end of the tunnel and it's getting brighter," Romney said.