A bilevel car (American English) or double-decker coach (British English and Canadian English) is a type of rail car that has two levels of passenger accommodation as opposed to one, increasing passenger capacity (up to 57% per car in extreme cases).
The use of double-decker carriages, where feasible, can resolve capacity problems on a railroad, 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.
Double deck trains are claimed to be more energy efficient, and may have a lower operating cost per passenger. A bi-level car may carry up to about twice as many as a normal car, if structure and loading gauges permit, without requiring double the weight to pull or material to build. However, a bi-level 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).
Double deck cars may not be usable in countries or on older railroad systems with low loading gauge, most notably the majority of the British railway 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.
History
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 upper deck 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 with the head height in the lower part of the carriage only ; the carriages had a capacity of 80 persons (third class) in a 2 axle vehicle of 13 tons fully loaded. The first all-steel Chemins de fer de l'État bilevels are an early example of split-level cars.
The Chicago, Burlington and Quincy Railroad placed bilevel Gallery cars in commuter service in the Chicago area in 1950. These were successful, and led to the Atchison, Topeka and Santa Fe Railway introducing long-distance Hi-Level cars on Chicago–Los Angeles El Capitan streamliner in 1954.
In Sydney, Australia the first 120 double-deck trailer cars entered service in 1964, being incorporated into the usual eight-car configuration used in Sydney, coupled to existing single-deck power cars. In 1968, four experimental double-deck power cars entered service, resulting in the world's first fully double-deck electric multiple unit passenger train.
Typical design The double-deck design usually includes lowering the bottom floor to below the top level of the wheels, closer to the rails, and then adding an upper floor above. Such a design will fit under more bridges, tunnels and power wires (structure gauge). For cost and safety, this design also minimizes car height (loading gauge) and lowers the centre of gravity.
Depending on train station platform heights, three designs can be used for entry – high platforms require use of a "split level" car design, where the doors are located on a middle level, with access into the upper or lower level branching off – with stairs or ramps going both up and down (sometimes this configuration includes a section of seating at the middle level in the entry section, with double levels only in part of the lengths of the car). For low train station platforms, a "two-floor" design with level entry onto the lower floor is used. Occasionally a third, very tall "two floors over-wheel" design is used. This is a traditional single floor car "with a second story" design which, when using a low platform, requires steps up to a traditional floor height and then internal stairs up to the upper floor.
Platform height and floor height issues
There are four important height measurements above the railhead: platform height, traditional floor height, downstairs floor height and upstairs floor height. Platform height determines the level entry height for wheeled objects, such as luggage, strollers, wheelchairs and bicycles. Platform height is ideally standardized across all stations the train serves. Traditional rail car floor height matters for end doors connecting to existing single floor rail cars. Downstairs or lowest floor height is primarily determined by the thickness of the beams connecting the span between the wheels and bogies (trucks) of a rail car. The upstairs floor or highest floor height is above the lowest floor and must fit under bridges and tunnels. Level entry floor height must match the platform height. Hopefully either the traditional or downstairs floor height already matches the platform height. Despite the name "bilevel" or "double-decker", for maximum compatibility the rail car will have up to four different floor heights. High platform design (Using outside steps to avoid having a level entry from the platform) is troublesome.
Common low-platform design Most low-platform double-decker trains have level entry onto the lower level of the car, allowing wheelchair access. There are two-floor heights (upstairs and downstairs) in these "bilevel" cars. There is a staircase between floors inside the car. Connecting doors between cars are either at the (higher) upper floor or at an intermediate level over the bogies. In the former case, connecting directly to a single level car causes drag and connecting door problems.
In the western USA, cars are of the upper-level-connection type. They use low-platform stations, because the traditional single floor trains all had exterior entry steps to maximize flexibility (emergency and temporary stops) and minimize infrastructure costs. There are no examples of two-floor platforms, so there are no platform doors on the upper floor. Car roof lines lengthwise are flat for connecting doors to the upstairs of bi-level cars. A Pullman-Standard / Bombardier Amtrak Superliner car is tall.
Uncommon very tall design There are several very tall bilevel cars (e.g. the Colorado Railcar DMU is tall). They typically are described as a traditional rail car with a second story. Most of these cars serve low platforms so they have exterior steps up to the traditional "over-wheel" floor height e.g. US . End doors connect at the traditional height of existing rolling stock. Some cars have upstairs end doors as well. Many of these cars also include outside balconies on either the upper or lower level. Upstairs and downstairs connect by interior stairs. These cars can fit most able people, but lack level entry. On almost all these cars the upper level consists of a full-length glass dome. Some cars are self-propelled multiple units so using traditional floor heights appears fixed. In towed cars, it is possible to lower the downstairs floor between the wheels/bogies so that level entry is possible with more than of added headroom and interior steps from that floor to the traditional floor.
Operators
Argentina
In 2005, Emprendimientos Ferroviarios (Emfer), Trenes de Buenos Aires (TBA (Trains of Buenos Aires)), National Institute of Industrial Technology and the Argentine National Government subscribed to a framework agreement to start the national designing and construction of bi-level electric trains. This was decided due to the overwhelming and increasing number of passengers using the gauge urban Sarmiento Line, serving the centre and east of Greater Buenos Aires. The first prototype was released in 2005, but mass-production only started in mid 2008. In 2013, these coaches were retired from the line and replaced with new CSR Electric Multiple Units, though it remains unclear if the Emfer trains will be moved elsewhere in the country.
In 2010, Emprendimientos Ferroviarios and Trenes de Buenos Aires presented non-engined double-decker coaches for a diesel interurban link between Buenos Aires and Mercedes city. Attending to different technical needs, the new coaches have only two simple non-automatic doors in the ends (instead of the two electric double doors in the middle) and were designed for low platforms.
For 2020, a public tender was launched by Trenes Argentinos to recover these double-decker coaches, for inter-urban and long-distance services, equipping them with reclining seats, USB inputs and other amenities.
Australia
In 1964, Tulloch Limited built the first double-decker trailer cars for use in Sydney. They ran with single deck electric motor cars. After the success of the trailers, Tulloch built four experimental double decker power cars in 1968.
From 1972, more double decker multiple units were constructed by Comeng and Goninan. These are now known as the S sets. All electric suburban and interurban trains in Greater Sydney are now double deck, though the Sydney Metro uses single deck carriages. All double deck carriages have two doors per side per carriage, with a vestibule at each end at platform height. The Sydney double deck commuter trains are high.
The Public Transport Corporation in Melbourne ordered a prototype Double Deck Development and Demonstration train in 1991, a modification of the Tangara design used in Sydney. It suffered frequent breakdowns and spent long periods out of use. It was withdrawn in 2002 and scrapped in 2006.
Austria Historically, bilevel cars were implemented in 1873 and were in use until World War I. In 1993, the railway company Graz-Köflacher Bahn started to use 15 cars for suburban transport around the city of Graz. In 1997, the national railway company ÖBB ordered 120 bilevel cars for the use in Eastern Austria and Vienna metropolitan area.
Canada
Canada's national passenger railway company, Via Rail, does not currently operate any bilevel coaches in its fleet, apart from the dome cars used on some long-distance services. These coaches include two levels over part of the length of the vehicle.
The Ontario Northland Railway operates a bilevel dome car on its Polar Bear Express service with two levels along the entire length of the vehicle.
The Bombardier BiLevel Coach was originally designed by Hawker-Siddeley Canada for the GO Transit commuter rail network in southern Ontario. It is now used by 14 different railway operators across North America, including all three of Canada's commuter rail systems. All train services operated by GO Transit and West Coast Express use Bombardier BiLevel coaches, while Montreal's Exo trains use a mix of Bombardier Bilevel, Bombardier MultiLevel and various single-level coaches.
The private rail tour company Rocky Mountaineer uses bilevel full-length dome cars built by Colorado Railcar.
China
The first bilevel train for China Railways was built by Sifang in 1958 as the Dongfeng diesel multiple unit, consisting of two diesel power cars and four bilevel coaches. After withdrawing Dongfeng DMU from use in 1982, China Railways redeveloped double-decker trains, the first of which rolled out from Nanjing Puzhen Rolling Stock Works in 1987 as locomotive-hauled coaches SYZ25 and SRZ25.