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1st phase creates new rail crossing, builds connector to Atherton
First phase of 120 Bypass improvements includes creating a 90-degree crossing of the railroad tracks for Woodward Avenue. DENNIS WATT/The Bulletin


The Bulletin

Woodward Avenue will T-intersect into Austin Road when all three phases of a plan to address safety, congestion, and operational issues surrounding the 120 Bypass and Highway 99 interchange are completed.

It is part of long range traffic flow changes coming to southeast Manteca when work is scheduled to start on the $131.5 million project in the fall of 2021.

The initial phase costing $52.5 million will replace the existing Austin Road overcrossing with a new bridge of two to four lanes. Not only will it allow for more traffic lanes on Highway 99 that is critical to resolving 120 Bypass issues but it will also take Austin Road over the Union Pacific Railroad tracks. At the same time the off-ramp from southbound Highway 99 to Austin will be closed until such time the third phase is completed. The same holds true for the northbound onramp from Austin to Highway 99.

Woodward Avenue at a point east of Atherton Drive will curve to the south so that it can cross the railroad tracks at 90 degrees instead of the current angle. Traffic signals would also be installed.

A temporary connector road to Austin Road will skirt the southern edge of a dairy that is just to the southwest of the tracks and existing Austin Road at-grade rail crossing.

The temporary connector road after swinging slightly to the south to avoid initially taking any of the dairy will then straighten out and head west to connect with the extension of Atherton Drive that is now being constructed. The temporary road will connect with Atherton north of Tannehill Drive and south of Heartland Drive.

The new Woodward Avenue configuration and connector road will remain in place until the third phase costing $53 million is built. That cannot take place until the second phase costing $26 million is completed. There is no funding earmarked for any phase beyond the first one. 

The vision Caltrans now has for the third phase is to swing Woodward Avenue south and then east cutting through the dairy to connect with Austin at the point where the temporary connector road will. A short connector street would then be built between Woodward as it curves toward Austin and Moffat Boulevard using the new at-grade crossing the first phase will put in place for the initial modification of Woodward Avenue’s alignment. That alignment of Woodward would require it to go through part of the dairy.

The goal is to award the first phase contract in the summer of 2021, start construction in the fall of 2021, and have work on the first phase completed by the fall of 2023.

The first phase involves:

uwidening the eastbound 120 Bypass to southbound Highway 99 from one to two lanes.

uremoving the Austin Road overcrossing and replacing it with a longer span that ultimately would allow eight freeway lanes plus auxiliary lanes on Highway 99. The replacement bridge would span the Union Pacific Railroad tracks as well eliminating the at-grade crossing on Austin Road.

uadding a new connector road Austin Road to East Woodward Avenue. The existing railroad crossing on East Woodard Avenue would be modified to confirm with the new connector road and provide access to Moffat Boulevard.

umodifying the existing northbound Austin Road exit ramp to conform to the higher overcrossing profile of the replacement bridge.

uclosing the northbound onramp and the southbound off-ramp for Highway 99 at Austin Road. The length of the closure is currently estimated at 9 years. Reopening of the replacement ramps will depend on the availability of funding for the third phase.

The second phase costing $26 million would:

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

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

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

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

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

The third phase costing $53 million would:

urestore the southbound off ramp by constructing a grade-separated braided ramp to eliminate weaving with 120 Bypass merging traffic.

uconstruct 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.

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

urelocate the Highway 99 frontage road for about 0.8 miles.

uadd 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.

uadd 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 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