After decades of waiting, motorists will be able to drive on the Willow Road interchange Saturday, following a ribbon-cutting ceremony Friday.

The Willow Road interchange and extension will open a route across the Nipomo Mesa to the coast, serving both mesa residents and tourists seeking faster access to Highway 1.

It also will lessen traffic jams on Tefft Street, a Highway 101 interchange that is one of the most congested in San Luis Obispo County, and increase access to Nipomo High school and Olde Towne Nipomo.

Assemblyman Katcho Achadjian, R-San Luis Obispo, who shepherded the project during his 12 years on the county Board of Supervisors, will be on hand, as will other community leaders.

The ribbon-cutting ceremony will take place at 3 p.m. and the public is invited. Parking can be accessed from Thompson Avenue.

The $20 million project was completed by Granite Construction of Santa Maria. According to the San Luis Obispo County Department of Public Works, it was funded by South County road improvement fees, the county, the San Luis Obispo Council of Governments, Prop 1B state and local partnership program funds, and the California Transportation Commission.

As part of the project’s mitigation for disturbances caused by construction, the Department of Public Works is developing a 22.8-acre oak woodland habitat on county property adjacent to the Dana Adobe. A contract to plant 4,000 acorns will be set later this year.