High-mast lighting is a tall pole with lighting attached to the top pointing towards the ground, usually but not always used to light a highway or recreational field. The pole that the lighting is mounted on is generally at least 30 metres (98 ft) tall, while the lighting consists of a ring surrounding the pole with one or several independent lighting fixtures mounted around it. Some units have the lighting surrounded by a circular shield to prevent or reduce light pollution or light trespass from affecting neighbourhoods adjacent to the highway. For a high mast to be made, it undergoes the processes of cutting, bending, welding, and galvanization.[1][2]
High mast is a broad term , it constitutes many types of poles ' some of them are enlisted below:- 1. Octagonal poles 2. High masts 3. Stadium masts 4. Monopoles 5. Transmission line towers 6. Microwave towers 7. Umbrella masts 8. Various other special projects 9. Swage Poles.
While designing a high mast very first thing is the material selection, there are various things that are to be considered while deciding material for a high mast. 1. Purpose 2. Velocity of wind 3. Composition of soil 4. Type of foundation Purpose is the main parameter for designing anything. If a high is to be used for usual street pole and the material we are using is 14mm thick sheet then the excess material is engaged in the purpose for no use. In some places the velocity of the wind is severe which will in one or other way damage the poles or the masts if subjected continuously to the wind. That is more the velocity more the thickness and less the velocity thinner the sheet. In same way the composition of soil and type of foundation as well affect the design of the masts.
The very important thing while designing a mast is the concept of development of surfaces.