In the northern half of the route, it is also known as Kirker Pass Road and then Railroad Avenue.

The route begins near the Interstate 680/Highway 24 junction, at the westbound entrance to Highway 24 at Ygnacio Valley Road, although this portion is actually signed as Hillside Avenue.

It then changes signage to Ygnacio Valley Road through an interchange with I-680 and continues though downtown Walnut Creek and Heather Farm Park.

[1] The road then enters Concord through Lime Ridge Open Space and continues into the Clayton Valley neighborhood.

It then enters Pittsburg, where it becomes Railroad Avenue at the Buchanan Road intersection.