Double-stack rail transport

In addition, the well car design reduces damage in transit and provides greater cargo security by cradling the lower containers so their doors cannot be opened.

Southern Pacific Railroad (SP), and Robert Ingram, of SeaLand, debuted the double-stack intermodal car in 1977.

[1][2][3] At first it was slow to become an industry standard, then in 1984 American President Lines, started working with the Union Pacific Railroad and that same year, the first all double-stack train left Los Angeles, California for South Kearny, New Jersey, under the name of "Stacktrain" rail service.

Double stack requires a higher clearance above the tracks, or structure gauge, than do other forms of rail freight.

Double-stack cars are most common in North America where intermodal traffic is heavy and electrification is less widespread; thus overhead clearances are typically more manageable.

Outside North America some rail routes have been built or upgraded to such standards as to allow both electrification with overhead wires and double stacking.

[citation needed] Intermodal containers shipped by rail within North America are primarily 53 feet (16.15 m) long, with trailer-on-flat-car (TOFC) units used as well.

[14] Low bridges and narrow tunnels in various locations prevent the operation of double-stack trains until costly upgrades are made.

Some Class I railroad companies in the U.S., often in partnership with government agencies, have implemented improvement programs to remove obstructions to double-stack trains.

Standard gauge railways in North America and China must use special well cars to lower the center of gravity,[20] fit within the loading gauge and in China allow double stack trains to run under specially heightened overhead lines.

[23] Experiments in India for double stacking using flatcars under 25 kV AC overhead lines set 7.45 m (24 ft 5+1⁄4 in) above rail have begun with funds given by Japan.