Excerpt from
en.wikipedia.org/wiki/San_Diego%E2%80%93Coronado_Bridge:
The San Diego–Coronado Bridge, locally referred to as the Coronado Bridge, is a pre-stressed concrete/steel girder bridge fixed-link, crossing over San Diego Bay in the United States, linking San Diego with Coronado, California. The bridge is signed as part of State Route 75.
The principal architect was Robert Mosher. Mosher's job was to build a bridge that would provide transportation, allow ships access to the bay, and serve as an iconic landmark for San Diego. Mosher proposed a basic box and girder style bridge for the framework, with a prestressed concrete and steel deck sitting atop steel girders and supported by towers. Mosher decided to make an orthotropic roadway, which used a stiffening technique that was new to the United States; it increased the strength and resistance of the bridge. As a result, the bridge was strong and eliminated the need for additional superstructures over the deck to disperse weight.
Construction on the San Diego–Coronado Bay Bridge started in February 1967. The bridge required 20,000 tons of steel (13,000 tons in structural steel and 7,000 in reinforcing steel) and 94,000 cubic yards of concrete. To add the concrete girders, 900,000 cubic yards of fill was dredged and the caissons for the towers were drilled and blasted 100 feet into the bed of the bay.
The bridge opened to traffic on August 3, 1969, during the celebration of the 200th anniversary of the founding of San Diego.[8][12] The 11,179-foot-long (3,407 m or 2.1 mi) bridge ascends from Coronado at a 4.67 percent grade before curving 80 degrees toward San Diego. It is supported by 27 concrete girders, the longest ever made at the time of construction.
