The City of Los Angeles is the owner of 533 structures, which include: 124 vehicular, 65 pedestrian 2 bikeway, and 19 railroad bridges, viaducts, and grade separations; 18 tunnels, and 5 miscellaneous structures that span waterways, roadways, railroad tracks, and valleys between prominent topographical features. Twenty-nine of these structures have been determined to be eligible for listing by the National Register of Historic Places (NRHP).

In December 2000, the City Council approved a $307 million Bridge Improvement Program (BIP), created within the Seismic Bond, to strengthen and upgrade 83 city-owned bridges. BIP was envisioned to be a long term continuous program, similar to the Bureau of Engineering's Street Program, to improve all bridges within the jurisdiction of the City.

The program is tasked to seek new sources of funding as they become available and to program new projects by working closely with Caltrans, LADOT, Metro, and FHWA staff. Funding is typically comprised of Highway Bridge Program (HBP) funds, with Local Seismic Safety Retrofit Program (LSSRP) state funds and Seismic Bond city funds serving as the local match. These funded projects are then leveraged to obtain additional Metro Call-for-Projects dollars and city Proposition C matching funds to cover expanded scopes of work such as bikeway and pedestrian improvements.

One of the 13 projects is the replacement of 6th Street Viaduct, a $400 million undertaking. With other adjustments, including an infusion of funding from the city's Capital Improvement Expenditure Program, the current total authorized budget of the entire program, stands at approximately $900 million.