Project
Description
SR120/Union Road Interchange Project
1st Diverging Diamond Interchange (DDI) in California.
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)
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.
Construction
Schedule
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.
Project Hotline: 209.707.3470
Project
Updates
Wednesday, November 25th: California’s First Diverging Diamond Interchange Opens
Ribbon Cutting Ceremony for California’s first diverging diamond was held Thursday, November 19th. The gathering was small, and attendees followed social distancing guidelines.
The DDI is unique in that it will reduce traffic and collisions on Union Road by shifting traffic to the left side of the road, before being shifted back to the right, eliminating any left-hand turns through the intersection. Residents and area travelers can learn how to navigating this ingenious design by watching this simulation video on the project website.
As we complete the final steps prior to opening, we ask that you expect delays and proceed with caution to ensure the safety of the traveling public and construction crews.
The City of Manteca is committed to delivering safe and efficient transportation facilities and improvements to the greater Manteca area.
California’s first diverging diamond interchange just debuted in Manteca
Even though it looks like something Hot Wheels would have designed, the diverging diamond interchange is actually expected to make the Union Road interchange safer.
MANTECA, Calif. — California’s first diverging diamond interchange (DDI) has finally debuted in Manteca.
Other states, like Nevada, have already installed a number of these unique designs over the years, but Manteca just cut the ribbon on on California’s first. That being said, drivers will still have to wait until Nov. 25 before they start cruising through it.
Its innovative design might look intimidating, but it’s meant to make traffic more “stop and go” for people crossing Union Road at Highway 120.
“I think that they’re going to be very happy with what we’ve provided them and it’s going to increase operability, and throughput and potentially capacity down the road…,” said Rob Shackelford, an engineer on the project with Dewberry.
Adding onto that, traffic safety takes a step up by reducing the potential accident locations from 26 to 14. Shackelford said there’s less opposing traffic and less opportunities for a T-bone style crash.
“With the diverging diamond, you’re not getting those,” he said. “Yes, you’re coming in and you’re merging at a lot of different locations, but you’re not getting those severe opposing angles of attack between two vehicles.”
The design is also safe for pedestrians and bicycles with a 10-foot-wide trail within the interchange that limits how many times they’ll interact with a car.
In the simplest terms, a DDI has drivers enter from the right side of the road, cross to the left side as they go through the interchange, and cross back again to the right.
This crisscross pattern keeps traffic moving through the intersections and provides free left-hand turns for drivers heading on and off the freeway.
It might look confusing, but the concept is fairly simple. If you want to make a left-hand turn at the interchange, stick to the left lane and you’ll get a free left-hand turn. If you want to make a right-hand turn, stick to the right lane and you’ll get a free right-hand turn.
“If you’re an attentive driver and you understand the rules of the road, you should be able to navigate this no problem, but you need to abide by the rules of the road so to speak,” Shackelford said.
California’s First Diverging Diamond Interchange To Wrap Construction In Manteca Before Thanksgiving
MANTECA (CBS13) – The first-ever interchange of its kind in California is set to open in Manteca three months early.
A diverging diamond interchange has been talked about for decades in Manteca and officially went under construction in June 2019.
Crews are putting the finishing touches on the project, which is located on Union Road over Highway 120 – right alongside Teri Candelaria’s home.
“I think everybody’s ready, it’s been crazy,” Candelaria said.
The project got its name because it looks like a diamond from overhead. It works like a roundabout by decreasing the number of conflict or collision points between vehicles by shifting traffic to the left side of the road, before being shifted back to the right – eliminating any left-hand turns through the intersection.
“When you look at the flow of traffic, at first it might seem daunting, but I myself personally have driven on them in other states and really you don’t even realize what’s happening if you just follow your traffic lanes and follow your traffic lights,” said Skip Allum with Caltrans.
City leaders said the interchange is more cost-effective, allowing the city to retain the existing overcrossing structure while saving time and money.
“We have ten years to do two more of these in Manteca. That’s the goal,” Manteca Mayor Benjamin Cantu said.
The new interchange also offers a separate pedestrian and bike path.
“I don’t know if it will help with the commute just yet,” John Pereira said. “It gets crazy in the mornings and the evenings are just as difficult.”
Construction will wrap on the interchange on November 25. It’s a nice present in time for the holidays, according to Candelaria.
“It looks way better than it did and so hopefully it will keep it smoother,” she said.
California’s First Diverging Diamond Interchange Opens on November 25, 2020
California’s First Diverging Diamond Interchange (DDI) located at SR 120 / Union Road broke ground in June 2019. This unique interchange project was scheduled for completion in March 2021, but due to COVID-19 and excellent teamwork, the Contractor (Teichert Construction) was able to reduce construction time by nearly four months and reduce the project costs by approximately $150,000. The City of Manteca will open this ingenious interchange design on November 25, 2020.
The DDI is unique in that traffic on Union 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 resulting in a reduction in collisions. A simulation video designed to demonstrate how to safely navigate this diverging diamond interchange, benefits, images, and opening details are available on the project website, mantecaddi.net.
The City of Manteca is committed to delivering safe and efficient transportation facilities and improvements to the greater Manteca area.
Call the project hotline with any questions or concern and a project team member will get back to you – 209.707-3470.
Union Road Interchange Full Closure September 9, 2020 – November 25, 2020
Crews will close Union Road Interchange to include closing of Union Road between Daniels Street and Atherton Drive,
SR 120 westbound off-ramp and SR 120 eastbound on-ramp to all through traffic.
Closure will begin at 12:01AM on September 9, 2020 and extend through November 25, 2020.
Exception: Access to emergency vehicles will be maintained at all times.
The lengthy interchange closure will substantially reduce construction time and complete the project faster while improving safety to the public to prepare the interchange for reopening.
For Eastbound Closure Details Click Here
For Westbound Closure Details Click Here
Call the project hotline with any questions or concern and a project team member will get back to you – 209.707-3470.
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