Planned Callahan Tunnel Closure Begins Friday

Starting late Friday, some drivers will have to find a new route to Logan Airport.

The state is closing Boston's Callahan Tunnel for a complete overhaul.

The work, as part of a $19.3 million contract, is expected to last until March 12, 2014, though Transportation Secretary Richard Davey said work could be completed ahead of schedule.

"We will actually have within the contract a number of incentives to encourage the contractor to finish ahead of schedule and penalties in the unlikely event that they are off-schedule," Davey said Monday.

During the closure, which was first announced in June, the state will take extra steps to mitigate the traffic impact. The Callahan carries 28,000 vehicles a day, and its closure will most affect drivers coming from north and south of Boston on Interstate 93.

The MBTA will run extra buses and Blue Line trains to Logan during off-peak hours. Rush-hour MBTA service will remain the same, since trains and buses are already running at full capacity, state transportation officials said.

For those driving, the state Department of Transportation recommends drivers take the Ted Williams Tunnel, or the Tobin Bridge to Route 1A South, to reach Logan Airport, with adjustments to traffic light timing on Route 16 to ease the flow of increased traffic.

The state will also open a bypass road in South Boston currently open only to commercial vehicles, as well as a HOV exit near South Station that will help drivers from the South Shore reach the Ted Williams Tunnel.

The repair work comes after a 100-pound panel fell onto the roadway inside the tunnel in December 2012. A subsequent investigation pinned the blame on corroded framework, prompting workers to test 2,400 wall and ceiling panels in the tunnel; 117 were removed.

As part of the incentive-laden project, upon completion the construction agency will receive an extra $71,000 per day the contract is completed ahead of schedule. It will be assessed a $71,000 penalty for each day construction goes beyond the March 12 completion date.