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Interchange plans subject of workshop Wednesday

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Plans call for a second transition lane from the eastbound 120 Bypass to southbound Highway 99.

HIME ROMERO/The Bulletin/

POSTED July 31, 2017 1:13 a.m.

Capacity for traffic transitioning between the 120 Bypass and Highway 99 heading to and from Ripon would double in volume under a Caltrans plan.

You can get a glimpse at what the state has in mind for the Highway 99 interchanges with the 120 Bypass and Austin Road during a workshop Wednesday, Aug. 2, from 5 to 8 p.m. at the Manteca Transit Center, 220 Moffat Boulevard.

The plans are in response to regional concerns about congestion and the high number of accidents and fatalities connected with movements through the 120/99 interchange. 

The workshop gives people the opportunity to see the plans, discuss various features with the design team, and to make comments. Caltrans is working with the City of Manteca and the San Joaquin Council of Governments.

Given the overall project carries an $81.6 million price tag and is not fully funded it will likely need to be done in phases. Funding Caltrans has identified so far comes from a combination of sources. That includes state money tied to Proposition 1B bond proceeds, Senate Bill 1, State Transportation Improvement Program, and Inter-regional Improvement Program. Federal funds as well as San Joaquin County Measure K sales tax proceeds are also being used.

The goal is to provide traffic congestion relief and improve interchange operations.

The interchange has become a regional priority given the congestion impacts commuters up and down the Highway 99 corridor and crimps the movement of goods. Most of the deaths and injuries — 11 deaths, 815 injuries in 1,261 accidents over a seven-year period — do not involve Manteca residents. 

The CHP handled 240 overall accidents in 2016 with about a hundred of those crashes involving injuries. That reflects an accident every 1.5 days that is serious enough to require a CHP response. The bulk of the accidents — and where almost every death occurs — is in the eastbound lanes in the 1.5-mile stretch starting midway between the Union Road and Main Street interchanges and the Highway 99 transition ramps.

Back in 2010 an accident requiring CHP response happened every 2.8 days on the 120 Bypass.


What the project entails

The project as outlined follows:

*It would double the capacity to handle eastbound 120 Bypass traffic heading south on Highway 99 toward Modesto.

*It would double the capacity to handle northbound Highway 99 traffic heading west on the 120 Bypass toward Main Street.

*It would have the exit lane for Austin Road for traffic traveling east on the 120 Bypass start where the southbound Highway 99 transition lane now starts and then parallel the transition land and Highway 99 before swinging to the southwest to intersect Moffat. It would then continue as a two-lane road and swing back heading east to T-intersect with Austin Road.

*It would have the exit lane for Austin Road for southbound Highway 99 traffic start just past the crossover bridge for the 99 to 120 Bypass westbound and 120 Bypass to Highway 99. That ramp would then become a bridge over the 120-99 transition lanes before joining the Austin Road exit ramp that starts on the 120 Bypass to create a two-lane ramp as it continues paralleling the 99 freeway,

*It widens the 120 Bypass from a point west of Main Street to the Highway 99 interchange to three lanes in each direction. Lanes would be added on the inside. That will also require the 120 Bypass bridges over Van Ryn Avenue as well as Moffat Boulevard and the Union Pacific Railroad tracks to be widened to three lanes in each direction as well.

*It would create a new Austin Road northbound on-ramp at a T-intersection with the ramp first heading to the southeast and curving back under the freeway. It will parallel the northbound Highway 99 freeways and part of the transition ramp from northbound 99 to the westbound 120 Bypass until a point where traffic originating on Austin Road that wants to head to the 120 Bypass can do so at a braid connecting it to the northbound 99 to westbound 120 Bypass.  Traffic from Austin Road wanting to head north on Highway 99 would continue on Austin Road onramp and merge with the freeway north of the where the transition ramp from the eastbound 120 Bypass merges with northbound Highway 99.

*Moffat Boulevard would no longer connect directly to Austin Road. There would, however, still be an onramp to southbound Highway 99 that would be accessed from a connector road to Austin Road.

*A new one off ramp would be built from northbound 99 to Austin Road

*The Frontage Road that intersects with Austin Road would be shifted to the east.

*Highway 99 southbound from the 120 Bypass would be widened from four to five lanes.

*Highway 99 northbound from Austin to the 120 Bypass would be widened from four to five lanes.

*Highway 99 to a point south of Austin Road would be widened from six to eight lanes of traffic and shifted to the east to avoid the Union Pacific right-of-way that will be double tracked to accommodate extending Altamont Corridor Express service into Ceres by 2023. 

*The Austin Road bridge across Highway 99 would also be extended across the railroad tracks to eliminate an at grade track crossing much like was done with Jack Tone Road in Ripon.

*Austin Road across Highway 99 will be widened from two lanes to four lanes and include left turn pockets much like the new Lathrop Road bridge that’s part of the Highway 99 interchange.

*Woodward Avenue would no longer connect with Moffat due to the need to move the railroad crossing further south for the off ramp traffic to reach Austin Road.


For more information use the Caltrans hotline at (209) 464-4350, Ext. 1, or send email to

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