Motorists traveling in both directions on Highway 46 East will be detoured onto the newly constructed traffic lanes between Airport Road and Geneseo Road beginning Friday.
The $30 million project, expected to be complete in late 2010, is contracted to Papich Construction of Pismo Beach.
The detour will allow crews to continue rebuilding the two existing lanes along the highway and constructing the two wild life crossings along with several drainage systems, according to Caltrans.
Electronic message boards will be posted to alert motorists of the detour, which is expected to be in effect through the end of the project.
All county road and driveway connections will remain open to cross traffic during the detour.