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Manteca could have states first diverging diamond
An existing diverging diamond interchange.

In the not-to-distant future you may drive the wrong way on Union Road across the 120 Bypass and not worry about getting a ticket.

It’s because Manteca is thinking a tad out of the box when it comes to increasing the capacity of the Union Road/120 Bypass interchange and saving up to $10 million at the same time.

Manteca is looking at a diverging diamond interchange instead of upgrading the existing structure to a partial cloverleaf.

Traffic lanes cross on either side of the bridge structure of a diverging diamond interchange so northbound traffic would cross the bridge on the west side instead of the east side with the southbound lanes on the east side instead of the west side. Once they clear the bridge they are switched back.

The on and off ramps along with the flipping of the lanes creates two semi-diamond shaped intersections on either side of the bridge. This eliminates the need for traffic signals for both directions on Union Road as well as that coming from the 120 Bypass avoid needing any  traffic signals to exit an off ramp or to get into an on ramp.

The design could slash as much as $10 million from the $25 million estimated cost of converting Union Road into a partial cloverleaf.

Other advantages of a diverging diamond interchange according to Advanced Transportation Solutions/American are:

 Fewer conflict points (14 for diverging diamond design, 26 for conventional design).

 Better sight distance at turns.

 Traffic calming features when desired.

Additional right of way is rarely needed.

Virtually no driver confusion based on a study and observation of existing diverging diamond design interchanges.

Construction time is reduced.

Wrong way entry to ramps extremely difficult.

Pedestrian crossings are shorter.

Maintenance of traffic is simplified during construction.

There are 57 such interchanges now in place in the United States. The closest is in Reno on Interstate 580 at Moana Lane.

Public Works Director Mark Houghton noted the interchange will provide safer bicycle and pedestrian passage across the 120 Bypass.

The project is being funded primarily with redevelopment agency fund earmarked for the project. It will require some development fees.

 Six consulting firms competed to serve as the primary consultant on the project. Mark Thomas & Company of Sacramento was selected to do the work.