The commissioner may make schedules of intrastate rates for railroads for the transportation of sand, gravel, crushed rock, and other materials to be used in the construction or maintenance of public roads and streets by or under the direction of public authorities, which rates may be lower than those charged for transporting the same kind of freight for all other purposes.
1957 c 943 s 27; 1971 c 25 s 67; 1976 c 166 s 16; 1980 c 534 s 20; 1998 c 403 s 29