Kuldīga Observation Tower

A lattice tower, or truss tower, is a freestanding vertical framework tower. This construction is widely used in transmission towers carrying high-voltage electric power lines, in radio masts and towers (both self-radiating towers and those that support aerials) and in observation towers. Its advantage is good shear strength at a much lower weight than a tower of solid construction would have as well as lower wind resistance. In structural engineering, the term lattice tower is used for a freestanding structure, while a lattice mast is a guyed mast supported by guy lines. Lattices of triangular (three-sided) cross-section are most common, particularly in North America. Square (four-sided) lattices are also widely used and are most common in Eurasia. A lattice towers is often designed as either a space frame or a hyperboloid structure. Before 1940, they were used as radio transmission towers especially for short and medium wave. Occasionally lattice towers consisting of wood were utilized. The tallest wooden lattice tower was at Mühlacker, Germany. It had a height of 190 metres (620 ft) and was built in 1934 and demolished in 1945. Most wood lattice towers were demolished before 1960. In Germany, the last big radio towers consisting of wood were the transmission towers of the Golm transmitter and the transmitter Ismaning. They were demolished in 1979 and 1983 respectively. The tallest free-standing lattice tower is the Tokyo Skytree, with a height of 634 metres (2,080 ft). The Petronius Compliant Tower is the tallest supported lattice tower at 640 metres (2,100 ft), being partially submerged. The city most renowned for lattice towers is Cincinnati, Ohio, which features four towers above 274 metres (899 ft) in height. Tokyo is the only other city in the world that has more than one above that height. The majority of the tallest steel lattice towers in the world are actually built in water and used as oil platforms.