Figure 15.25 shows the growth of maximum spans by year. It is obvious that in the 60-year period from the Golden Gate Bridge (1937) to the completion of the Storebelt Bridge in Denmark (1997), the rate of increase in maximum center span has been steady and gradual for catenary suspension bridges. The increase in span during this time frame is 27%. However, the Akashi Kaikyo Bridge completed in 1998 represents a 23% increase in span over the Storebelt Bridge, or a 55% increase over the Golden Gate Bridge. A similar change in cable-stay bridges occurred with the Normandy Bridge (1994) with a 42% increase in span over the Yang Pu Bridge (1993).
The Akashi Kaikyo Bridge, along with the contemplated Messina Straits and Gibraltar Straits Bridges, represent a dramatic change in span rate growth. It should be pointed out, however, that the schemes for the contemplated 5,000 m span Gibraltar Straits Bridge are a pure catenary suspension as well as several hybrid types, Fig. 15.26.
(Lin, T. Y. and Chow, P., Gibraltar Straits Crossing A Challenge to Bridge and Structural Engineers, Structural Engineering International, Journal of the IABSE, vol. 1, no. 2, May 1991.)