Manteca is getting ready to do a rare feat among California cities these days — open its third new freeway interchange in just six years.
The first phase of the Highway 99/120 Bypass Connector Project overseen by the San Joaquin Council of Governments will open to traffic following a Wednesday, June 17, 10 a.m. ribbon cutting.
At the same time, a second transition lane from the eastbound Bypass to southbound Highway 99 is expected to be open.
It is that second transition lane that is key to reducing the Bypass bottleneck and by extension making it safer to drive that is at the heart of the two-phase endeavor.
A Caltrans study indicated the three-mile Bypass stretch between Airport Way and Highway 99 had an accident rate more than seven times higher than the average freeway mile in California.
The primary reason was traffic cutting into the one transition lane.
The existing 1955-era Austin Road overcrossing had to be replaced to accommodate a smooth transition for the additional lane as well as a future second transition lane going from northbound Highway 99 to the westbound Bypass.
It will mark the third new interchange to open in Manteca since 2020.
The replacement Union Road diverging diamond interchange — the first in California — opened in 2020.
Then in 2024, the new McKinley Avenue interchange opened to give Manteca four interchanges a mile apart along the 120 Bypass.
The June 17 ribbon cutting also marks another first for Manteca — the city’s first railroad grade separation. The replacement four-lane bridge will also span Moffat Boulevard and the Union Pacific tracks.
Gary Singh has been a council member or mayor for all three ribbon cuttings.
More importantly, he has represented Manteca on the SJCOG board since before the Union Road interchange was upgraded.
Singh noted the efforts of former Manteca Mayor Steve DeBrum and former Councilman John Harris, both who served on SJCOG, helped to make the 120/99 project possible.
He added Mayor Ben Cantu championed the city putting up an additional $4 million to widen the replacement interchange to four lanes to serve future development in southeast and east Manteca.
SJCOG is the regional county agency that has harnessed the half-cent countywide Measure K sales tax to transform how people commute and get around their communities whether it is by freeway, major arterials, heavy rail, bus, bicycles of walking.
It also helps provide local road repair dollars plus a number of projects dealing directly with pedestrian safety.
It may go unmentioned on June 17, but the ribbon cutting also marks a major accomplishment for SJCOG.
It completes the overhaul and widening of the Highway 99 corridor from upgrading the Stanislaus River bridge crossing in Ripon all the way to a point north of Stockton.
Measure K allowed the county to be first in line for state matching bond money that not only widened the corridor to six lanes starting back in 2010, but also has removed the last bridge overcrossing from Highway 99’s first appearance as a freeway in 1955.
Singh noted surface street improvements in southeast Manteca connected with the project will make it easier for residents to access the freeway and move around the city.
The project includes the realignment of Woodward, traffic signals on Woodward at Atherton as well as Moffat, traffic signals on Austin for the new road between Atherton and Austin and the elimination of stop signs on Moffat that backed up afternoon commute traffic for a quarter of a mile on a routine basis.
Second phase design
is underway for project
The northbound on-ramp and the southbound off-ramp at Austin will be restored in the second phase.
The design work that is fully funded includes adding a second transition lane from northbound 99 to the westbound Bypass.
It also will make the 120 Bypass six lanes between Highway 99 and the 120 Bypass.
That work is dependent on securing funding.
The current timeline is to try to finish the work in five years.
To contact Dennis Wyatt, email dwyatt@mantecabulletin.com
