Study on the Breakeven Point of Human Transportation Distance in Mechanized Construction of 220kV and 500kV Overhead Transmission Lines

Mechanized construction is an important part of State Grid Corporation, and mechanized construction of overhead transmission lines in mountainous areas is a major challenge. The breakeven point of human transportation distance is an important indicator for selecting tower locations for mechanized construction in mountainous areas. This paper is based on a survey of the foundation types of mechanized construction in mountainous areas, discussed the cost calculation differences between mechanized construction of overhead transmission lines and conventional construction and analysis the breakeven point for typical terrain conditions of 220kV and 500kV lines, the results show that: (1) the breakeven points are between 63-125m on 220kV transmission line, and that of 500kV transmission line is 233-421m which is higher than that of 220kV and 110kV. (2) The breakeven point of rock anchor foundation is greater than that of mechanized pile foundations on same condition, indicating that the economic benefits of rock anchor foundations are relatively high.