Structures / Illinois Street Bascule Bridge
- Creegan + D’Angelo Civil and Structural Engineers
Bascule bridges are a unique bridge type with many different systems to lift and lower a bridge. The Port of San Francisco required submittal of Design-Build team qualifications to “qualify” teams that were then invited to submit the proposed Bridge plans and project costs. The Port used a “Lowest Project Cost” criteria to select the Design–Build team.
Reinhard Ludke’s economic solution of a non-counterweighted, hydraulic lift bascule bridge, allowed the Creegan + D’Angelo/Shimmick Construction team to “win” the project.
The movable span section is a bascule type single leaf bridge using hydraulic pistons to lift the non-counter weighted steel girder/concrete deck bridge. The approach bridge spans consisted of a conventional concrete deck steel girder bridge spans supported by concrete pile caps with battered, deep, steel piles.
The bridge was a Design-Build project delivery of new 520-foot long railroad, freight and truck bridge with a 85-feet bascule span located over Islias Creek on Illinois Street, San Francisco. Bridge and railroad engineering was provided to the owner, Port of San Francisco, with construction by Shimmick Construction. The bridge consists of a steel girder combined rail and truck bridge with a movable span across the navigable channel. The movable span section was bascule type using hydraulic pistons to lift the steel girder/concrete deck bridge with hinge bearing. The approach bridge spans consisted of steel girder spans supported by concrete pile cap with battered, deep, steel piles. The functions of the bridge includes pedestrian and bicycle accessibility, bridge lift control and motor building, and railroad and vehicle traffic. The project team included bascule bridge mechanical design/engineering specialists, railroad design, electrical, geotechnical, and traffic engineering. The Port of San Francisco is the owner. An accelerated Design- Build schedule was imposed on the project with liquidated damages for failure to complete project within 700-days of authorization to proceed. Permits with the BCDC, Army Corps of Engineers, and the City of San Francisco were required for completion of the project.
Illinois Street includes a single centerline railroad track and two 11 feet wide traffic lanes. The bridge is designed to support Cooper E 80 railroad loads and HS20-44 truckloads. The site has deep soft bay mud deposits so concrete filled steel pipe piles will be used for bridge piers. Vertical load capacity of each piles is 350 tons.
Two trunnion mounted hydraulic cylinders were used to lift and lower the bridge. The cylinders are supported on the flanking span and connected the bascule span crank arm. A single steel bridge stay, from the crank arm to the bridge lifting girder quarter span point delivers the lift moment to the structure. The trunnion axle also includes a 48 inch diameter torsion beam that creates uniform rotation across the bridge and is a primary structure component for emergency operation in event one cylinder loses power. Cylinders capacity is specified so in an emergency, only one of the two hydraulic cylinders, can lift and lower the bridge.
- 2007 SEAONC Award of Excellence
- 2007 SEAOC Structural Engineering Excellence Award
- 2008 CELSOC Engineering Excellence Honor Award
- 2008 ASCE SAN FRANCISCOO SECTION - Outstanding Transportation Project of the Year
- Non-counterweight single leaf bascule using 2 - 500 ton hydraulic cylinders to raise and lower the bridge.