Whenever, to carry out any work ordered under RCW 81.53.010 through 81.53.281 and 81.54.010, it is necessary to erect and maintain posts, piers, or abutments in a highway, the right and authority to erect and maintain the same is hereby granted: PROVIDED, That, in case of a state highway the same shall be placed only at such points on such state highway as may be approved by the state secretary of transportation and fixed after such approval by order of the commission.