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Land acquisition phase nears for 120 Bypass & 99 interchange improvements
120 Bypass logo

Caltrans is getting ready to move forward to start the land acquisition segment for the first phase of the $131.5 million upgrades for the Highway 99/120 Bypass interchange designed to enhance safety and reduce traffic congestion.

Manteca Councilman Gary Singh said Thursday the San Joaquin Council of Governments received a progress report on the $54.4 million first phase that is targeted to break ground in the fall of 2021.

Singh, who serves as the city’s representative to SJCOG that coordinates highway projects in the county and also oversees the Measure K half cent transportation sales tax, noted funding for the first phase is secured.  Singh added he is working with various agencies to secure funding for subsequent phases in a bid to get all of the improvements in place within a 10-year time frame.

Most of the land acquisition needs are for a new connector street from Austin Road to the eastern end of Woodward Avenue that would be realigned to cross the Union Pacific Railroad tracks at a 90-degree angle to create a true T-intersection with Moffat Boulevard to enhance safer and better traffic flow.

Land will also be needed for the Austin Road bridge replacement that will take it from two lanes to four lanes with turning lanes such as was done with the Highway 99 interchange at Lathrop Road. The replacement bridge will also clear the railroad tracks. Traffic to reach Moffat Boulevard would take the new connector street to be built that would tie into Woodward Avenue. Land will also be needed for ramp improvements on the east side of the freeway that will require the relocation of the Frontage Road.

The first phase improvements would:

*widen the connector from the eastbound Bypass to southbound Highway 99 to two lanes.

*replace the existing Austin Road overcrossing with a new bridge that would also go over the Union Pacific Railroad tracks.

*swing Woodward Avenue south to connect with Austin Road.

*relocate the current at-grade Woodward Avenue crossing of the railroad tracks to reach Moffat Boulevard so vehicles cross the tracks at 90 degrees. This would be a new, short road that only goes from the new alignment of Woodward Avenue to Moffat Boulevard.

*potentially temporarily shut down the southbound off ramp and northbound on ramp at Austin Road and the Highway 99 interchange.

*build a new northbound off ramp to Highway 99 at Austin Road.

The configuration would allow traffic to use Moffat Boulevard — which would flow under Austin Road — to access southbound Highway 99 as it currently does.

The second phase costing $26 million would:

*widen the connector from northbound Highway 99 to the westbound 120 Bypass from one to two lanes.

*convert the existing structure crossing Highway 99 to the 120 Bypass to two lanes.

*construct a new separation structure to serve eastbound 120 Bypass traffic to the northbound Highway 99 connector ramp.

*add a westbound auxiliary lane on the 120 Bypass from the Highway 99 interchange to Main Street.

 *add an eastbound auxiliary lane on the 120 Bypass between Main Street and Highway 99.

The third phase costing $53 million would:

*restore the southbound off ramp — if it ends up being closed in the first phase — by constructing a grade-separated braided ramp to eliminate weaving with 120 Bypass merging traffic.

*construct the entrance ramp from Austin Road to northbound Highway 99 and to the westbound 120 Bypass as a loop ramp that will separate traffic movements to Highway 99 and the 120 Bypass.

*relocate the northbound Highway 99 exit ramp to Austin Road to accommodate the loop onramp.

*relocate the Highway 99 frontage road for about 0.8 miles.

*add an auxiliary lane in each direction on Highway 99 from the 120 Bypass to about 1.7 miles south of Austin Road by shifting the median away from the Union Pacific right-of-way and relocating the frontage road.

*add an auxiliary lane in the existing median of the eastbound 120 Bypass from Main Street to Highway 99 to provide a dedicated lane to connect to the new 120/99 separation structure.

The high cost of the third phase design is reflected in it being necessary not to impede traffic flow and create a major safety hazard from the 120 Bypass south to 99 and from 99 going north to the eastbound 120 Bypass.

In order to do so the ramp for southbound Austin would start for eastbound 120 Bypass traffic at a point near the Bypass crossing of Moffat Boulevard and the railroad tracks while  the ramp for southbound 99 traffic to access Austin would start prior to the 120 Bypass connector flyover.

Caltrans has estimated the second and third phases could start construction in March 2030 and be completed by September 2031. Since it is highly dependent on funding, it is possible there could be a nine year gap between the two phases.


To contact Dennis Wyatt, email