City Of Manteca
SR120 / Union Road Interchange

Project
Description

SR120/Union Road Interchange Project
1st Diverging Diamond Interchange (DDI) in California.

The City of Manteca in partnership with Caltrans District 10 and SJCOG are working to improve safety and traffic flow at interchange located at State Route 120 and Union Road. 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.

The new interchange reduces conflict points between vehicles and moves traffic more efficiently through the interchange. The DDI is unique in that traffic on the local road is shifted to the left side of the road, before being shifted back to the right. Eliminating any left hand turns through the intersection. Upgrading to the unique DDI configuration provides significant cost savings and safety benefits for both vehicles and pedestrians.

Union Road is a key crossing of State Route 120 in the City’s bicycle master plan. The new Class I path will provide a 10-foot wide grade-separated trail that eliminates all bicycle/vehicle conflict points within the interchange to provide safe and efficient passage for bicycles, pedestrians, and other non-motorized travel.

Auxiliary lanes will be constructed between Airport Way and Main Street on eastbound and westbound State Route 120 to provide for increased traffic flow during peak times.

Project Partners:

Benefits of a
Diverging Diamond Interchange (DDI)

Safety is a priority. This Diverging Diamond Interchange will reduce the number of conflict points from the existing 26 down to 14. Most importantly, the more severe collision types (crossing/T-bone) are reduced form 10 down to two.

Existing overpass does not have designated pedestrian or bicycle access. The new interchange will provide a Class I shared-use path and Class II bike lanes. The new Class I path will provide a 10-foot wide grade-separated trail that eliminates all bicycle/vehicle conflict points within the interchange providing safe and efficient passage for bicycles, pedestrians, and other non-motorized travel.
Cost effective solution allows for the project costs to be greatly reduced compared to other interchange types. Also allows for the existing bridge to remain.
Improved traffic operations on Union Road. This project will 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 due to a reduction in collision points from 26 to 14 and separate bicycles and pedestrian lanes.

Provide Pedestrian Access

Provide Bicycle Access

Reduce Traffic Congestion

Reduce Conflict Points

Funding

Shared Funding for this project is provided by City of Manteca, and San Joaquin Council of Governments.

Construction
Schedule

Project Completion 95%

Project Schedule

June 25, 2019

Groundbreaking Event

July 2019

Construction Begins

November 25, 2020

New DDI opens

Project Notes

Delays are anticipated weekdays between 6:00am – 4:00pm on Union Road between Atherton Drive and Daniels Street. Please be aware of increased truck traffic in the area as a result of the interchange improvements.
Traffic Detours and Closures will be posted in advance on this website in the Updates Section and the City of Manteca Facebook Page.
Work will generally take place between 6 a.m. and 5 p.m. Monday through Friday. Night and/or weekend work may occur as necessary.