The next diverging diamond interchange — where lanes crisscross each other on the bridge deck — is being pursued in Lathrop.

 The City of Lathrop is planning the diverging diamond interchange (DSI) at Louise Avenue and the Interstate 5 interchange on/off-ramps.

According to City Manager Stephen Salvatore, this one will be similar to California’s first diverging diamond interchange built on the 120 Bypass at Union Road in Manteca but “at-grade,” he said at Monday’s Lathrop City Council meeting.

“Union Road is elevated,” Salvatore said. “Our (DDI) will be at-grade because there’s already a bridge structure going over I-5. There will be no elevated concrete structures – it’ll be like driving underneath the freeway like you normally do.

“We’re just changing the pattern,” he said.

Tracy is in the process of building the state’s second DDI on Interstate 580 and the Internation Business Parkway.

Manteca is in initial planning stage for two more DDIs along the 120 Bypass — one at Airport Way and the other at Main Street.

The proposed design of the Louise & I-5 Interchange Project will see the widening of the road underneath the freeway with the roadway crossing in and out at two sections of the interchange on / off ramps.

The compact interchange design of the DDI could improve the flow of traffic and reduce delays, according to the consultant presentation.

By reducing the speed, motorists would see the elimination of conflict points – as in reducing the right of way acquisitions – in turn, improving the safety and reducing severity of vehicle crashes.

Plans also include bicycle / pedestrian accessibility – there are no current bike lanes – with the installation of bicycle lanes coupled with improved sidewalks.

The total cost of the project is estimated at $34.8 million, with about $27 million of that being for construction, using local funds. The city is still exploring outside funding sources.

The next step for the project is getting the circulate draft project report and the draft environmental document completed in October.

The final design could be accomplished in July while the right of way certification being done by October 2026.

If all goes accordingly, construction could begin in the spring of 2027 and completed by the fall of 2028.