Designed to last more than a 100 years
The new landmark footbridge will provide pedestrian access between the city’s spectacular Balboa Park and the picturesque natural harbor of San Diego Bay, spanning six railroad tracks and several lanes of vehicle traffic. Designed to serve over 100 years, the bridge is built with a material that enables reliable, maintenance-free service over the design life in the maritime Pacific climate: duplex stainless steel of grade Outokumpu 2205. “Because the bridge is close to the San Diego Bay, high resistance to corrosion was required,” says Dan Fitzwilliam, a senior bridge engineer at the lead design engineering firm T.Y. Lin International.
Aesthetics and strength
Another key reason for the material choice was aesthetics. “We wanted something with a high-quality finish because pedestrians would be interacting with the bridge at a much slower pace than one would passing under in a vehicle,” says Dan Fitzwilliam. Also contributing was the characteristic strength of duplex. “The stainless steel had a load carrying capacity, too,” he continues, “so the stainless had to have high strength.” Duplex stainless steel features almost twice the strength compared to austenitic stainless steel.
Recommended by consultant and fabricator
Outokumpu was found by the steel fabricator, with a role played also by the consulting company. “We weren’t aware of 2205 previously. When we started to list the criteria for the San Diego bridge, we contacted TMR Consulting to aide us in the search. They were instrumental in the final material selection.” TMR Consulting is a metallurgy consulting firm based in Pittsburgh, PA, which regularly works with Outokumpu in a consultant role.
The San Diego Harbor Drive Bridge joins a large family of pedestrian bridges built with Outokumpu materials and expertise. This includes the Singapore Marina Bay Pedestrian Bridge, the Celtic Gateway bridge in Wales, as well as the Padre Arrupe Bridge adjacent to the Guggenheim museum in Bilbao. Vehicular bridges using Outokumpu duplex include the Stonecutters Bridge in Hong Kong and the Gateway Bridge in Brisbane, Australia.