H&H was selected to develop a unique bascule bridge design for the replacement of the historic “Big Blue” Strauss heel trunnion bridge in Victoria, British Columbia. Our scope of work included conceptual through final design, preparation of contract documents, and construction support.
The visual character of the bridge along with the innovative structural and mechanical systems combine to make the new structure a one-of-a-kind movable bridge. This uniqueness of design was combined with a specially developed project delivery model. The delivery model established an integrated approach to developing the various mechanical and electrical systems concurrently with the structural design. H&H was selected to develop the design based on our ability to integrate complex structural/mechanical and electrical designs for heavy movable structures.
H&H selected a bogie system using a multitude of wheels, similar to that used on retractable roofs and cranes, to distribute the load evenly to the structure. A closed-loop hydrostatic transmission with high torque, low speed hydraulic motors driving the rack pinions directly engaging the racks provides power to raise or lower the bridge. Electronically controlled variable speed AC pump motors are used to control acceleration, speed, and deceleration. A PLC is used to control the drives, monitor switches, and provide diagnostics. Remote monitoring and diagnostics are available through an Ethernet connection. The bridge was designed to a very high seismic standard, meeting the most stringent current codes in North America. The design of the new bridge allowed the bridge to be available to traffic after a 1000-year earthquake event.
The deck is constructed with a series of orthotropic panels (a steel plate with welded ribs for added support) that are spliced together and connected with the floor beams. The deck and floor beams were connected to each truss to create a fully welded structure.
The bridge opened to traffic on March 31st, 2018, and received a 2019 Diamond Award for Engineering Excellence from ACEC New York in the Structural Systems Category.
Photo Credit: Darren McQuitty