A three-month detour is expected to begin tonight on northbound Highway 101 in the South County as part of the Willow Road Interchange Project.
Northbound traffic will be diverted onto a paved center median so construction can proceed on the new Willow Road under-crossing.
The detour will be in place 24 hours a day. It will begin sometime between 9 p.m. tonight and 6 a.m. Wednesday morning, according to Caltrans.
A separate project in which crews have been working to extend Willow Road between Pomeroy Road and Hetrick Avenue could be completed in the next few weeks, according to Caltrans.
In 2013, Willow Road will also be extended from Hetrick Avenue to Thompson Road to establish a direct link on the Nipomo Mesa from Highway 1 to Highway 101.
The contractor for the $42 million project is Granite Construction of Santa Maria.