Bilevel car

The bilevel car (North American English) or double-decker train (British English) is a type of rail car that has two levels of passenger accommodation, as opposed to one, increasing passenger capacity (in example cases of up to 57% per car). In some countries such vehicles are commonly referred to as dostos, derived from the German Doppelstockwagen.

The use of double-decker carriages, where feasible, can resolve capacity problems on a railway, avoiding other options which have an associated infrastructure cost such as longer trains (which require longer station platforms), more trains per hour (which the signalling or safety requirements may not allow) or adding extra tracks besides the existing line.

Bilevel trains are claimed to be more energy efficient, and may have a lower operating cost per passenger. A bilevel car may carry about twice as many as a normal car, without requiring double the weight to pull or material to build. However, a bilevel train may take longer to exchange passengers at each station, since more people will enter and exit from each car. The increased dwell time makes them most popular on long-distance routes which make fewer stops (and may be popular with passengers for offering a better view).

Bilevel cars may not be usable in countries or older railway systems with low loading gauges. This includes much of the rail network in the northeast of the USA and almost the entire British rail network. In some countries such as the UK new lines are built to a higher than the existing structure gauge to allow the use of double-deck trains in future.

Double deck carriages date to at least as early as the second half of the 19th century. In France several hundred voitures à impériale with seats on the roof were in use by the Chemins de fer de l'Ouest, Chemins de fer de l'Est and Chemins de fer du Nord by 1870, having been in use for over 2 decades; the design was open at the sides with a light roof or awning covering the seats. In the 1860s M.J.B. Vidard introduced two-storied carriages on the Chemins de fer de l'Est, with a full body, windows, and doors; the same design lowered the floor of the lower storey to keep the center of gravity low. Vidard's carriages had a total height of 13 feet 8 inches (4.17 m) with the head height in the lower part of the carriage only 5 feet 5 inches (1.65 m); the carriages had a capacity of 80 persons (third class) in a 2 axle vehicle of 13 tons fully loaded.

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