Traffic along Hwy 1 through Morro Bay will be reduced to one lane in each direction starting Friday, Caltrans officials say.
The partial closure comes as crews begin work to rebuild the northbound Toro Creek Bridge.
The left lane of both north and southbound Hwy 1 will be closed through the area.
Later in May, both directions of traffic will be diverted onto the southbound Toro Creek Bridge so crews can complete the project, officials say.
The project is funded by the 2017 California Senate Bill 1.