This unique project features the first Diverging Diamond Interchange (DDI) designed in the State of California. Mark Thomas led the design of this innovative interchange, working closely with the City of Manteca and Caltrans District 10 on the preparation of the project approvals. The new DDI configuration was not in the Caltrans Highway Design Manual (HDM) – our team coordinated with Caltrans District 10 and Headquarters to gain acceptance of the design concept, and ultimately, final design.

We also incorporated a ribbon path – a grade separated Class I bike path through the new interchange – to eliminate all bicycle/vehicle conflict points, as Union Road is a key crossing of SR 120. The new Class I path provides a 12-foot wide trail with slab bridge structures underneath the entrance/exit ramps and on the SR 120 overcrossing.