A transmission tower (colloquially termed an electricity pylon in the United Kingdom and parts of Europe, an ironman in Australia, and a hydro tower in English Canada) is a tall structure, usually a steel lattice tower, used to support an overhead power line. They are used in high voltage AC and DC systems, and come in a wide variety of shapes and sizes. Typical height ranges from 15 to 55 metres (49 to 180 ft), though the tallest are the 370 m (1,214 ft) towers of a 2700 metres long span of Zhoushan Island Overhead Powerline Tie. In addition to steel, other materials may be used, including concrete and wood. The products of the Proposed Fabrication units are covered by well designed and fabricated structures for a. state electricity boards for the purposes of electricity supply (i,e) a) power transmission Towers, TV and Radio Towers, Telecommunication Towers, b) Railway and Highway bridges etc. c. Industrial structures etc. Some transmission towers combine these basic functions. Transmission towers and their overhead power lines are often considered to be a form of visual pollution. Methods to reduce the visual impact include undergrounding. Tower structures can be classified by the way in which they support the line conductors. Suspension structures support the conductor vertically using suspension insulators. . Strain structures resist net tension in the conductors and the conductors attach to the structure through strain insulators. Dead end structures support the full weight of the conductor and also all the tension in it, and also use strain insulators. Where the conductors are straight, a tangent tower is used. Angle towers are used where a line must change direction. Structures are classified as tangent suspension, angle suspension, tangent strain, angle strain, tangent dead end and angle dead end.