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Flyover in Stockton could help ease blocked crossings at 2 Manteca locations
concept diamond
A concept rendering of the proposed $237 million flyover at the Stockton Diamond that would eliminate an at-grade crossing by taking Union Pacific trains over the Santa Fe Railroad line

A diamond flyover could be a Manteca motorist’s best friend — at least for a brief period of time.

And it could also make rail travel the best choice for Mantecans and others nearby that commute to Sacramento when ACE passenger trains start pulling out of downtown in 2023.

That’s because a rare railroad project 15 miles away from Manteca to the southeast of downtown Stockton that’s moving through the environmental review process could reduce the potential for sidelined trains to block the Woodward Avenue and Industrial Park Drive crossings.

The project would replace the at-grade crossing of Union Pacific and Santa Fe railroads at the Stockton Diamond with a flyover bridge for the north-south Union Pacific Railroad.

The Stockton Diamond now clogs up freight movements. As a result train movements heading into Stockton from UP’s Fresno line that crosses 10 Manteca streets and the Oakland line that crosses 3 Manteca streets are often slowed down. The Stockton Diamond is the busiest and most congested at grade crossings of two railroads in California.

The biggest impact is on trains that are placed on sidings in Manteca that cross Woodward Avenue and Industrial Park Drive. The congestion created by the at-grade crossing can ripple through Manteca.

Building the flyover to replace the at-grade won’t eliminate sidelined trains blocking crossings in Manteca. It will, however reduce the amount of additional blocked crossings that increased freight and passenger traffic will bring in the coming years.

Union Pacific expects the Oakland line — that impacts the Louise Avenue, Yosemite Avenue, and McKinley Avenue crossings — to see train movements go from 32 today to 75 or a 120 percent increase that also includes ACE trains going from 8 to 10 a day.

The biggest impact, however, is on the Fresno line that slices Manteca in half. The current daily train census will triple going from 20 trains a day to 60 including six ACE trains.

Further complicating train flow is the fact passenger movements take priority. That could, depending on timing and frequency of freight trains, when  CE service to Ceres starts in 2023 increase the number of freight trains sidelined in Manteca.

Originally the San Joaquin Rail Commission was exploring double tracking from Manteca to Ceres as a precursor to ACE service. Since then, it was determined the $234 million flyover in Stockton would provide more bang for the buck of limited dollars in terms of moving goods and passengers on a regional basis.

Double tracking through Manteca would have reduced the time somewhat for Union Pacific trains that can be as long as 8,000 feet from blocking crossings as train traffic can move in both directions at the same time. However, double tracking in many areas have proven to be more treacherous as people (particularly pedestrians)  — assuming that a train has passed and that it is safe to proceed — forget there is a second track. 

Both Union Pacific and Santa Fe have major intermodal yards in the Manteca area where truck trailers are transferred to and from train flatcars.

The UP facility is nestled between Lathrop and Manteca and accessed from Roth Road. It has been approved to almost triple in size to 2,186 truck movements a day at complete buildout that is expected in 40 years.

The 2001 expansion of the Santa Fe facility 12 miles northeast of Manteca between Austin and Jack Tone roads has increased that railroad’s intermodal capacity in San Joaquin County from 120,000 to 300,000 units annually.

Based largely on the intermodal traffic that is critical to South San Joaquin County’s growing strategic advantage of being the primary distribution center for the 19 million people in the Bay Area Mega Region, on the UP line cutting Manteca in half, train traffic — including ACE trains that will start running to and from Ceres in 2023 — will triple from an average of 20 a day to 60. That is the equivalent of a train on average every 24 minutes as opposed to the current average of once every hour and 12 minutes.

The flyover at the Stockton Diamond will do little if anything to mitigate increased train traffic through Manteca. Without double tracking that is not currently on the table, tripling train traffic through Manteca is likely to ultimately triple the amount of time trains are sidelined and blocking the Woodward and Industrial Park crossings.

The frequency of moving trains blocking other crossing will triple as well.

Manteca is unique as there is no other city in the Central Valley with as many crossing where trains are moving through their communities at a high rate of speed.


To contact Dennis Wyatt, email