Generally speaking, the surface of the bearing columns on both sides of the subway catenary is not galvanized, and it is usually painted or sprayed with plastic. This is because the galvanized surface is rough and easy to be scratched and punctured, which makes the surface lose its protective function and leads to rust and corrosion of the column. Spray painting or plastic spraying can effectively protect the surface of the column, prevent it from being eroded by oxidation and corrosion, and prolong the service life of the column.