The Legislature also approved the collection of a toll surcharge to pay for a signature span and a bike path. The type of signature span was selected via a design competition. An overriding principle of the design is to achieve harmony with the existing western span, with the Golden Gate Bridge and with the profile of Yerba Buena Island. To accomplish this the height of the tower was restricted to 530 ft., the same height of the towers of the double suspension bridge western span from Yerba Buena to San Francisco. Further the catenary shape of the suspension cable echoes those of the other two famous bridges of the Bay and the topography of the Island.
Further drama is achieved by asymmetry of the main and back spans.
The asymmetry is achieved by placing the tower near to Yerba Buena Island, resulting in a back span of about 590 ft. and a main span, stretching toward Oakland, of about 1270 ft. The steel tower is designed to be seismically efficient through a configuration of four legs or columns connected by struts. The legs are designed to remain elastic during the design earthquake with minor damage confined to easily-replaced struts. The tower remains stable up to a displacement of approximately 5 times that of the design earthquake. Twin cables are anchored at the outside edges of the orthotropic deck.