Work to rebuild the collapsed portion of Highway 236 near Jameson Creek Road will require the complete closure of the two lane road.
About six feet of the roadway washed out during heavy rainfall earlier this month.
Caltrans needs to drill three holes in the area to obtain geotechnical design information they need to build a retaining wall.
The first of the holes were drilled Tuesday, requiring one-way traffic controls.
Today, crews will need to close the highway entirely from 9 a.m. to 6 p.m. in order to drill the remaining two holes.
If they are unsuccessful, a second full closure of the highway will be necessary Thursday, March 26 to complete the task.
Electronic signs will be posted in Boulder Creel on Highway 236 and Highway 9 to alert motorists about traffic conditions.
Caltrans urges motorists to use a detour around the road work. Maps will be provided by flaggers at the scene.
For information about this and other Caltrans projects in Santa Cruz County, call 423-0396 or visit www.dot.ca.gov/dist05/maint/road/upscr.htm.