Three lanes of Highway 101 will be closed at Airport Boulevard for four nights this week, Caltrans said. Each direction will be closed separately.
Southbound 101 will be closed Wednesday and Thursday nights from 11 p.m. to 5 a.m.
Drivers will have to exit on Shiloh Road, turn left and continue to Old Redwood Highway, where they will turn right. From there, drivers will turn right onto Fulton Road and continue to the southbound 101 on-ramp.
Northbound 101 will be closed Friday and Saturday night from 11:59 p.m. to 6 a.m.
Drivers will exit on Fulton Road, turn left on Old Redwood Highway, turn left on Shiloh Road and continue to the northbound on-ramp.
Caltrans also opened on Monday a new southbound off-ramp at Airport Boulevard. The off-ramp, however, only allows a right turn onto westbound Airport Boulevard while crews replace the bridge over the highway.
Southbound 101 drivers wishing to exit onto eastbound Airport Boulevard should exit at River Road, turn right on Fulton Road and right on Airport Boulevard.
"This will allow crews to speed up construction of the new bridge," Caltrans spokesman Allyn Amsk said.
The altered driving conditions are necessary while crews work on the $28.7 million project to improve the Airport Boulevard interchange and eliminate the Fulton Road on- and off-ramps, Amsk said. The project should be completed by the end of next year.
Caltrans has completely closed Highway 101 in the past, most recently last month when the freeway at South Petaluma Boulevard was shut for four days while crews worked on a new overpass.