Suspension bridge types about each type of bridge. Provided the cables are of sufficiently high quality, suspension bridges are suitable for the longest spans. However, their construction costs are high, so that usually they are economical only for spans in excess of 1000 feet. Shorter spans often are constructed for aesthetic reasons. The economy of longer span suspension bridges is due to their relatively low weight, but because of the greater flexibility that comes with low weight these bridges are more suitable as road bridges than railroad bridges. Suspension bridge types A suspension bridge is any type of bridge that makes significant use
Pontoon (boat) of the world, especially in Africa. Pontoon ferries may be motorised, such as the Kazungula Ferry across the Zambezi River, or powered by another boat, or pulled by cables. A type of ferry known as the cable ferry ("punts" was what they were called in the medieval times and in modern Australia and New Zealand) pull themselves across a river using a motor or human power applied to the cable, which also guides the pontoon. Pontoons may support a platform, creating a raft. A raft supporting a house-like structure is a houseboat. The flotation tubes of rigid-hulled inflatable boats are