The steel truss Manthey Road bridge has spanned the San Joaquin River since 1926.

The days for the bridge at Mossdale Crossing — that once had a moveable section to accommodate passing boats — are numbered.

The Lathrop City Council when they meet Monday at 6 p.m. are being asked to approve the initial project study for a replacement bridge and a mitigated negative environment impact declaration.

A $25.9 million replacement bridge will be built further downstream in alignment with the Golden Valley Parkway on River Islands.

Golden Valley Parkway would swing through the planned River Islands employment center where a Valley Link station for commuter rail service connecting to the BART station in Pleasanton-Dublin is planned.

Golden Valley Parkway then will swing to the southwest and connect to a future interchange on Interstate 205 where Paradise Road is currently crossing beneath the freeway.

Once the new bridge is in place, the now 100-year-old Manthey Road bridge will be removed.

A Caltrans study in 2012 assigned the Manthey bridge a sufficiency rating of 7. 1 out of 100 and determined that it was structurally deficient and functionally obsolete.

The existing bridge does not provide standard lane or shoulder widths, and its superstructure cannot be widened to accommodate current roadway and other transit safety standards for pedestrians, bicyclists, and shoulder widths.

The new bridge would be 523 feet long and 53 feet wide. There would two 12-foot travel lanes, 8-foot shoulders, and sidewalk separated from traffic by a concrete barrier.

The new roadway would extend south from Brookhurst Boulevard, cross the San Joaquin River on the new bridge, and connect with Stewart Road in the River Islands development.

Intersection improvements would be constructed at Sadler Oak Drive.

Traffic signals would be installed at the Golden Valley Parkway intersections with Brookhurst Boulevard, Sadler Oak Drive, and Stewart Road.

The project would maintain access to Mossdale Crossing Regional Park.

Manthey Road would terminate in a cul-de-sac near the park to accommodate vehicle and bus turnarounds. The separate existing pedestrian bridge that is above the South San Joaquin Irrigation District pipeline would remain in place.

It will be the first new bridge built across the entirety of the San Joaquin River when the River Islands Parkway was put in place in 2012. The bridge was not connected to a roadway until several years later.

Cambay Group needed to get the bridge in place as a number of required permits from state and federal agencies that took nearly 10 years to secure started expiring.

The River Islands Parkway bridge was the first new bridge across the San Joaquin River since 1960. There will eventually be a second, two-lane bridge built next to it.

Bridges over the San Joaquin River have a long and storied history in Lathrop. While the golden spike for the transcontinental railroad was actually hammered into the ground by Leland Stanford in Utah in May of 1869, the bridge at Mossdale Crossing wasn’t completed until September. That made it the last segment to connect the West Coast of the United States with the existing Eastern rail network that terminated at Council Bluffs, Iowa.

That bridge has since been replaced. It is still in operation today as a working train crossing.

To contact Dennis Wyatt, email dwyatt@mantecabulletin.com