By allowing ads to appear on this site, you support the local businesses who, in turn, support great journalism.
Supervisors seek $28M for 2nd phase of 120 Bypass/99 interchange improvements
woodeward swing
Sometime within the next two to three years Woodward Avenue east of Atherton Drive will curve to the south through this almond orchard to connect with Austin Road and a short road connector that will cross the tracks to connect with Moffat Boulevard.

The last mile of the eastbound 120 Bypass has gotten all of the attention and rightfully so.

Caltrans last year in doing the environmental work for a three-phase $131.5million solution they’ve come up with to address the congestion at the 120 Bypass/99 interchange noted the accident rate in the final mile of the Bypass as you approach and pass the Main Street exit is six times the state average. It is where in 2018 an accident happened almost every 15 hours making it the deadliest — and most accident prone — segment of freeway in the Northern San Joaquin Valley.

The design factors that may contribute to that carnage are being addressed in the $54 million first phase targeted to break ground in the fall of 2021. That phase has roughly a two-year construction timeline.

There is an “up and coming” problem stretch, however, that won’t be addressed unless funding is secured for the $28 million second phase. It is northbound Highway 99 as it approaches the 120 Bypass.

It is here on many weekday mornings that not only does the outside lane often comes to a stop but so does the middle lane as a number of drivers — just like they do on the 120 Bypass — wait until the last possible minute to move over so they can access the transition ramp to the westbound 120 Bypass.

The accident rate on this section of Highway 99 is now slightly more than double the state average and getting worse with each passing year.

It is why the San Joaquin County Board of Supervisors when they meet today is considering making funding for the second phase a Top 10 county priority. Staff is recommending it be ranked third on the countywide list, from the perspective of the Board of Supervisors, that deserves consideration for state funding.

Topping the county list is Grant Line Road west of the Tracy City limits west of Banta Road to Interstate 5 from two to four lanes at a cost of $20 million.

No.3 on their list is adding a high occupancy vehicle lane in each direction of Interstate 205 from Interstate 5 to the San Joaquin County line. The $300 million project would include closing the gap between 22 arterial crossings resulting in 11 joined bridges.


What second phase

of 99/120 work entails

The second phase of the 120 Bypass/99 interchange costing $26 million would widen the connector from northbound Highway 99 to the westbound 120 Bypass from one to two lanes.

It would also convert the existing structure crossing Highway 99 to the 120 Bypass to two lanes.  This will allow the adding of a westbound auxiliary lane on the 120 Bypass eastbound from the Highway 99 interchange to Main Street. It would operate similar to the auxiliary lanes that opened last month in both directions from Union Road to the Airport Way and Main Street interchanges.

It would allow for a long merge for traffic coming off southbound 99 to westbound 120 that now has its own dedicated lane. Targeted on Caltrans project list in 2035 or beyond would be a third travel lane in each direction in the center median.

The second phase would also construct a new separation structure to serve eastbound 120 Bypass traffic to the northbound Highway 99 connector ramp.



Impacts the first phase

will have on Manteca

Besides correcting the biggest issue — traffic congestion that triggers unsafe lane movements on the last mile of the eastbound 120 Bypass as it nears Highway 99 by adding a second transition lane to southbound Highway 99 and replacing the Austin Road overcrossing , the first phase will also address another safety issue — Moffat Boulevard and Woodward Avenue.

Given the intersection is a key component of addressing traffic movement off and on Highway 99 at Austin Road the subpar interchange comes under the umbrella of the $52.5 million first phase.

When Woodward Avenue crossed the tracks 25 years ago it was a lightly used country road. The part of Moffat Boulevard it connected with saw little southbound traffic as congestion as dangers on the Bypass during the afternoon commute hadn’t yet prompted a number of drivers to find alternative routes. At the same time traffic on northbound Moffat was extremely light. That’s because the left exit flyover lane from northbound Highway 99 that fed directly into Moffat at a point south of the present-day Crossroads Grace Community Church was still in place. What northbound traffic was on Moffat when it was passing Woodward Avenue originated in the countryside along Austin Road. It also was not high speed as it had a stop sign where only a left turn was possible to merge with traffic coming off the freeway from northbound 99.

The solution being built in the first phase will replace the Austin Road bridge with one that passes not only above the freeway but Moffat Boulevard and the Union Pacific Railroad tracks as well. At a point where roughly the almond orchards are today, a new alignment of Woodward Avenue would T-intersect with Austin Road. It will then head to the northwest in a gentle “S” curve until it connects with the current Woodward Avenue alignment just east of Atherton Dive.

A short connector street between the new Woodward Avenue alignment and Moffat Boulevard would be built so that it crosses the railroad tracks at a 90 degree angle instead of the less than optimum angle it does today.

One issue the Caltrans study notes and the project doesn’t address in any phase is operational issues at the Main Street off-ramp for eastbound 120 Bypass traffic.

The study indicates service has deteriorated below the standard levels. During some points of the afternoon commute traffic is also backed up to the freeway waiting for the signal to change to turn onto Main Street.

The City of Manteca has no project on the planning horizon to widen the Main Street interchange to four lanes and upgrade the ramps.


To contact Dennis Wyatt, email