There's only one bridge on the Oakland Terminal Railway, but it's a doozie. Built in 1938 as half of a wye shaped wooden trestle to carry SP red electric trains over the SP freight mains and Desert Yard throat, the flyover features 4% grades and sharp curves better suited to interurban electric cars than diesels and freight cars. Nevertheless, the wood, concrete, and steel structure is still getting the job done after 67 years. The freeway overpasses that now surround the flyover are the new I880 freeway, built in the late 1990's to replace the Cypress Structure that collapsed in the 1989 Loma Prieta earthquake.