Constructed in 1926, the Manthey Road Bridge is an approximate 126-foot long by 24-foot wide steel bascule truss bridge that spans over a portion of the San Joaquin River in the City of Lathrop. Previous removal of the counterweight changed the bridge from a cantilever span bridge to a simple span bridge, thereby reversing the forces in the top and bottom chord members and some web members.
Originally designed to accommodate 20-ton vehicles, the bridge was unsuitable for crossing by today’s 36-ton trucks. To prevent load posting of the bridge and to allow the bridge to remain in service, Cornerstone performed a comprehensive vertical load analysis using current live load design standards and provided strengthening of overstressed steel truss members. The connections of the truss members were checked and determined to be adequate. Strengthening of the top chord was accomplished by bolting cover plates on either side.