Highway 12 outside Sebastopol will be closed Friday night so that traffic can be diverted onto a newly built span of the Laguna Bridge, Caltrans announced.

The closure begins at 10 p.m. Friday and ends at 7 a.m. Saturday. Motorists will face detours while the shift is made.

Patti Lacey, manager at the Village Park mobile home park right next to the bridge, said last week that residents are prepared for delays.

“We just have to deal with it until it’s done,” she said.

The existing Laguna Bridge is being replaced because of underwater scouring and erosion. The 220-foot bridge, which spans the Laguna de Santa Rosa, was built in 1921 and widened in 1949.

The new span is being constructed to modern-day standards, with 12-foot lanes, 8-foot shoulders and 7-foot sidewalks in each direction. The work began this summer and will continue through 2017, including work on the northern, westbound half of the bridge.

Traffic is first being diverted onto the southern, eastbound half of the new bridge adjacent to the existing structure.

The construction work has resulted in the temporary loss of a turn lane onto Morris Street that Village Park residents used to merge into westbound traffic after they left the park.

“It really makes it hard to get out sometimes,” Lacey said.

The turn lane will return after the traffic shift onto the new bridge span, Caltrans spokesman Allyn Amsk said.

He said the mobile home park’s close proximity to the bridge has made the construction work more of a challenge.

“This has definitely been a challenge for everyone — Caltrans, the contractor and residents — during this phase of construction,” Amsk said.

The bridge replacement is a $9 million project. More than 23,000 vehicles cross the span on an average day.

The construction season is limited to between June 15 and Oct. 15 because of environmental regulations related to the Laguna’s sensitive wildlife habitat.

You can reach Staff Writer Derek Moore at 521-5336 or derek.moore@pressdemocrat.com. On Twitter @deadlinederek.

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