Caltrans reaches a milestone Friday night on Highway 101 when northbound traffic will be routed over the new Wilfred Avenue-Commerce Boulevard overpass in Rohnert Park.

The CHP says the switchover will start around 11 p.m. as construction crews close lanes and on and offramps intermittently to reconfigure the northbound lanes. So motorists should be extra careful from 11 p.m. until sometime early Saturday when the switch will be complete.

Southbound traffic is expected to be shifted over to the new overpass in a few days.