The detours are necessary because the bridge’s current westbound lanes are directly in the path of the new eastern span, spokesman Bart Ney told reporters at a briefing near the bridge this morning.
To accommodate construction of the new span, the existing lanes in both directions will be shifted south, starting with the eastbound lanes, and the part of the current bridge that is in the way will be demolished, Ney said.
The shifting will take place along a 1,000-foot-long stretch of the so-called “Oakland touchdown” section near the toll plaza.
The eastbound detour is scheduled to begin in late May and a westbound detour is expected to be in place early next year, Ney said.
“This is a pretty significant engineering effort,” Ney said.
He said the eastbound detour will result in an easier curve for motorists to negotiate but he said “any change is a concern” because the Bay Bridge is now 75 years old and motorists will have to change their long-standing driving habits.
If the work proceeds as planned, the new span will open up to six months ahead of schedule in 2013, he said.
The new eastern span originally was scheduled to open in two phases, with the westbound section opening in 2013 and eastbound lanes opening in 2014.
However, Ney said Caltrans is now planning for both directions to open at the same time in the fall of 2013.
He said Caltrans wants to open the new span as quickly as possible because “we want seismic safety sooner,” noting that its main goal is to try to make the Bay Bridge, which was damaged in the 1989 Loma Prieta temblor, more able to withstand earthquakes.
Jeff Shuttleworth, Bay City News