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Work starts in spring on 2nd transition lane to south- bound Highway 99 & on new Austin Road interchange
bypass traffic
Commuter traffic backing on the eastbound 120 Bypass.

The notorious traffic snarl on the eastbound 120 Bypass that worsens as you near the Highway 99 split is bad enough.

But that pales to the fact you are seven times more likely than the national average to get into a crash on the 120 Bypass than in a typical segment of freeway.

It is why Ryan Niblock has worked so diligently to get funding in place for the first phase of a $131.5 million solution addressing safety and congestion on the freeway as well as associated local Manteca traffic movements.

Niblock is part of a behind-the-scene multi-agency effort working in concert with elected leaders throughout the region to move toward ground breaking next spring to address the bottleneck that is slowing down not just commuters but also the movement of goods.

Niblock works for the San Joaquin Council of Governments. It’s the agency that has collected pennies via the countywide Measure K sales tax that has delivered San Joaquin major freeway and rail projects as well as underwritten a long list of local road projects and pumped up streets maintenance funds for the county’s seven cities.

One of his tasks is to line up and secure funding for road projects.

And when it comes to the first phase work costing $52.5 million he’s in the final stretch assuring when ground breaks officially in March or April of next year there is money to cover the tab. Once a $4 million federal grant that is being processed is secured the SJCOG board is expected to approve bonding against future Measure K receipts to cover the remaining $4.5 million.

The initial phase will essentially address the safety issue first. It involves adding a second southbound transition lane to Highway 99 and replacing the Austin Road overcrossing to allow it to happen.


Second phase work is

targeted to start in 2023

Niblock provided an update on the project during Thursday’s Manteca Rotary meeting at Mt. Mike’s Pizza.

He is already working on funding for the second phase expected to cost between $25 million and $30 million that involves adding a second transition lane to the 120 Bypass from Highway 99 northbound. That will address the growing issue of traffic backing up to Ripon during the morning commute.

The final phase pegged at $53 million will involve extensive braided on and off ramps for traffic movements from the eastbound 120 Bypass and southbound Highway 99 to Austin Road and from Austin Road to the westbound 120 Bypass and northbound Highway 99.

SCJOC is working on a “1B” phase that would restore the ramps on the north side of Austin Road that have to be removed to do the first phase work. Those ramps would be used until such time the third phase is completed.

“The decision was made to do (the work) in phases instead of waiting until all of the funding was in place so the safety issues could be addressed as soon as possible,” Niblock said.

The goal is to break ground on the second phase by spring of 2023.

He noted due to the size and complexity of the project motorists should expect construction work to take up to five years.

The work starting in the spring is just one of 50 projects including transit that are part of a concerted effort to improve traffic flow on the Northern San Joaquin Valley’s most congested commute corridor.

That corridor starts with Interstate 680 on the Alameda County line, continues onto Interstate 205, encompasses the Mossdale weave on Interstate 205, heads onto the 120 Bypass and then heads south on Highway 99 to the Stanislaus River.


What work the three

phases will involve

That first phase costing $52.5 million 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 would 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.

*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 would:

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

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

The third phase would:

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

*add new southbound off ramp and a new northbound onramp at Austin Road.

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.

A braided ramp system — designed on the same principle as the Interstate 680/Interstate 580 connector in Pleasanton when you are going toward San Jose — would be needed to take traffic from Austin to head onto 99 or the Bypass. Austin traffic bound for the westbound 120 Bypass would join the Bypass after passing below Highway 99 by merging with the southbound 99 to westbound 120 Bypass ramp. The Austin Road traffic heading north on 99 would join the freeway north of the Bypass/99 interchange.

The design will allow a future carpool lane project to be built on Highway 99 through the area eventually widening the freeway from six to eight lanes.

The current Austin Road overpass needs to be replaced in order to make things work. As it now stands it cannot accommodate any additional lanes passing beneath it on Highway 99.

The design will allow both lanes on the 120 Bypass to go south on Highway 99. Improvements will be made for a long merging area that will end south of Austin Road.


To contact Dennis Wyatt, email