Caltrans is shifting traffic lanes on Highway 101 in Petaluma this week. The overnight roadwork will take place Tuesday night through Saturday morning from 10:00 p.m. to 6:00 a.m. Caltrans says traffic lanes will be shifted to the center median, allowing work crews more space to convert the outside shoulders into traffic lanes. Caltrans is widening the highway to three lanes in each direction between Lakeville Highway 116 and Petaluma Boulevard North.