Rail freight is well standardized in North America, with Janney couplers and compatible air brakes. The main variations are in loading gauge and maximum car weight. Most trackage is owned by private companies that also operate freight trains on those tracks. Since the Staggers Rail Act of 1980, the freight rail industry in the U.S. has been largely deregulated. Freight cars are routinely interchanged between carriers, as needed, and are identified by company reporting marks and serial numbers. Most have computer readable automatic equipment identification transponders. With isolated exceptions, freight trains in North America are hauled by diesel locomotives, even on the electrified Northeast Corridor.