Caltrans will close the northbound Highway 101 offramp to East Washington Street in Petaluma Monday night and Tuesday morning for construction work.
The work will include shifting the ramp's two lanes from the right side to the left.
When the overall project is done, the ramp will have four lanes.
The ramp will be closed from 10 p.m. Monday until 5 a.m. Tuesday.
Caltrans urges drivers to slow down, use extra caution through the construction zone and leave a safe distance between their vehicle and the vehicle ahead of them.
For more information about the project, call the Caltrans message line at 510-286-5820.