Traffic in both directions will share the southbound bridge over State Route 116 in Petaluma starting Saturday and until a new bridge is finished later this year.
"Northbound traffic will to be shifted to the left across the median to the southbound bridge," Caltrans said in a press release. "There will be two northbound lanes and two southbound lanes sharing the same bridge. After passing over SR 116, northbound traffic will shift to the right and return to the original roadway."
Caltrans is replacing the bridges, which each have two lanes, no shoulders and were built in 1955. The new bridges will have three lanes in each direction and should be finished by mid-2015, Caltrans says on its website.
During the temporary lane shift, traffic directions will be separated by concrete barriers and the speed limit in the area will be 45 mph.
"It is essential for the safety of motorists and construction workers that this speed limit is observed," Caltrans said in the press release. "This speed limit will be enforced by the California Highway Patrol."
The construction will include the following lane closures:
- One lane of northbound Highway 101 will be closed from 10 p.m. to 6 a.m. Wednesday and Thursday nights, and from 10 p.m. to 7 a.m. Friday night.
- One lane of southbound Highway 101 will be closed from 10 p.m. to 4 a.m. Thursday night and 10 p.m. to 7 a.m. Friday night.
- The northbound Highway 101 offramp to State Route 116 will be closed from 10 p.m. to 6 a.m. Friday night.
- Both onramps from State Route 116 to northbound Highway 101 will be closed from 10 p.m. to 6 a.m. Friday.
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