Suspension bridge construct special towers, as the buildings can anchor the cables. Cable suspension may also be augmented by the inherent stiffness of a structure that has much in common with a tubular bridge. Typical suspension bridges are constructed using a sequence generally described as follows. Depending on length and size, construction may take anywhere between a year and a half (construction on the original Tacoma Narrows Bridge took only 19 months) up to as long as a decade (the Akashi-Kaikyō Bridge's construction began in May 1986 and was opened in May 1998 – a total of twelve years). Suspension bridges are
Pontoon effect Pontoon effect The pontoon effect refers to the tendency of a vessel whose flotation depends on lateral pontoons to capsize without warning when a lateral force is applied. The effect can be sudden and dramatic because pontoon boats usually cannot rely on the righting effect of a keel (which contains ballast). The vessel is stable and self-righting up to the point that the centre of gravity shifts past the centre of buoyancy of the ship and the vessel rapidly capsizes. The pontoon effect is theoretically possible whenever the vessel's entire weight exceeds the buoyancy of the pontoon(s) on either side.