City of Manteca Celebrates Ground Breaking of California’s First Divergent Diamond Interchange (DDI)


The Drake Haglan & Associates (DHA) team was on-site yesterday to facilitate the groundbreaking ceremony for the City of Manteca’s State Route 120/Union Road Interchange project. DHA is providing construction management, inspection, environmental monitoring, and public outreach services for the project in coordination with the City of Manteca, Caltrans, and Teichert Construction. The new Diverging Diamond Interchange is estimated to open in Fall 2020.

The State Route 120/Union Road Interchange Project will be the first Diverging Diamond Interchange in California (DDI). The project will improve safety conditions by constructing new on and off ramps, widening Union Road to 4 lanes between Daniels Street and Lifestyle Street, and providing a Class I shared-use path and Class II bike lanes.

Benefits of a Diverging Diamond Interchange

  • Cost effective solution allows for the project costs to be greatly reduced compared to other interchange types. This also allows for the existing bridge to remain.
  • Improved traffic operations on Union Road. This project will also construct auxiliary lanes on State Route 120 from Airport Way to Main Street.
  • Compact footprint by eliminating right of way acquisition.
  • Class I grade separated shared use path improves pedestrian and bicycle mobility. This accomplishes the City’s General Plan goal and closes a significant gap in the pedestrian network.
  • Safety is highly increased with a DDI. There are reductions in collision points and added safety to bicycles and pedestrians. 


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