San Francisco 4-Th Street bridge ready to be rolled on at high tide

Project Summary

The 90-year-old bascule 4-th Street bridge (also known as the Peter R. Maloney bridge), designed by Joseph Strauss of Golden Gate Bridge fame, underwent an extensive seismic retrofit and massive structural overhaul. After completion, it needed to be installed again over the Mission Channel in San Francisco. For the removal in 2003, see our Removal 4-th Street Bridge project page.

Early morning on May 12, 2005, using two sets of Goldhofer trailers, the bridge was slowly rolled onto the Dutra barge 217 at high tide, while ballasting the barge to control the heel. Once the bridge was completely on board, the barge was maneuvered into position, with the bridge pins over the bearing saddles. The barge was then ballasted down to a minimum freeboard of 12 inches. The tide did the rest. Once the barge was close to its support points, the trailers were lowered to make first contact. The load was fully transferred by additional ballasting and once free, the barge with trailers and support beams was pulled out from under the bridge at low tide.

Scope of Work

The project scope included:

• Verify feasibility of the proposed cargo barge;
• Check of barge stability throughout the various phases of rolling on and set down;
• Design of detailed ballast procedures for rolling the bridge onto the barge;
• Provision of on-site assistance during the bridge loading/installation operation.

Project Photographs

Trailers with bridge arrived at the ramp plates, ready to start rolling on.	Barge with bridge moved into position for lowering bridge.	Bridge pins lowered onto bearing saddles by ballasting and falling tide.	At low tide, after completion of load transfer, the barge was pulled out.