The San Diego–Coronado Bridge, locally referred to as the Coronado Bridge, is a prestressed 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. Description Construction In 1926, John D. Spreckels recommended that a bridge be built between San Diego and Coronado, but voters dismissed the plan. The U.S. Navy initially did not support a bridge that would span San Diego Bay to connect San Diego to Coronado. They feared a bridge could be collapsed by attack or an earthquake and trap the ships stationed at Naval Base San Diego. In 1935, an officer at the naval air station at North Island argued that if a bridge was built to cross the bay then the Navy would leave San Diego. In 1951–52, the Coronado City Council initiated plans for bridge feasibility studies. By 1964 the Navy supported a bridge if there was at least of clearance for ships which operate out of the nearby Naval Base San Diego to pass underneath it. To achieve this clearance with a reasonable grade, the bridge length was increased by taking a curved path, rather than a more direct path to Coronado. The clearance would allow an empty oil-fired aircraft carrier to pass beneath itit is not sufficient for Nimitz-class nuclear aircraft carriers in light load condition. 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