Double decker
|
|
A double-decker is a bus, airplane, train, tram, ferry or any public transit vehicle that has two levels for passengers, one deck above the other.
| Contents |
Bus
Doubledeckerferraridmg.jpg
Double-decker buses are taller than other buses. They are extensively used in the United Kingdom, where perhaps the most famous is the Routemaster used in London, which is now being phased out (as of 2005). Most of the buses in Hong Kong and about half in Singapore are double-deckers as well. A few are also used as tour buses, especially in New York and Paris.
Some double-decker buses have an open upper deck, with no roof and shallow sides. These are popular for sightseeing tours.
Airplane
The most popular double-deck airplane is the Boeing 747, although the top deck is smaller than the lower level. The new Airbus A380, however, has two decks extending the full length of the airplane.
Train
Because of the standard height of tunnels and overhead power wires, many double-deck trains set the bottom deck lower down between the trucks (bogies in UK parlance). At the entrance doors of the train there is just a single deck, above the bogies. From there one can go upstairs or downstairs. For example, for the DD-IRM (see below) it is one step up from the station platform to the entrance platform, and from there seven steps up or four steps down.
France runs double-deck cars on heavily loaded high-speed TGV services and commuter lines such as the Paris suburban RER.
Go_Train_046.jpg
Another advantage of bilevel gallery cars is the relatively low first step of the vestibule entrance to the car, which is 14 5/8" above the head of the rail. The advantage of this design feature is that commuter rail operators do not have to spend scarce funds on building high-level platforms; rather, a low-level platform is all that is necessary, at a far lower cost.
Other designs, including rolling stock made by Colorado Railcar Manufacturing, Budd, Pullman-Standard, Bombardier and others, house the entrance on the lower deck rather than an intermediate level. Amtrak Superliners are double-decker cars of this variety, housing the entrance about a step or so up from the lowest station platform level, or at the level of slightly higher platforms, and allowing passage from car to car through the upper corridors of the train. (Colorado Railcar Manufacturing, responsible for constructing the Princess cars on the Alaska Railroad, can be located online at [2] (http://www.coloradorailcar.com/).)
In some countries such as the United Kingdom, and also in the north-eastern region of the United States, the railway system cannot accommodate double-deck trains because the loading gauge is too small (i.e. bridges, tunnels, etc. are too low). An intermediate form of two-level seating arrangement has been tried in Britain (the Southern Railway's 4DD class electric multiple units), where the bottoms of the upper seats are above the heads of the people on the lower level, but the feet of the people above are not, see [3] (http://members.tripod.com/~dart75/bddscut.htm).
Double-deck trains often have curved windows upstairs. In the evening and in tunnels children love this for the distorting mirror effect.
In the Netherlands, there are two types of double-deck trains, the DDM and the DD-IRM, also called Regiorunner: see Trains in the Netherlands.
In Spain several lines of Cercanías (Renfe's commuter rail service) use double-deck trains.
All electric commuter trains in Sydney are double deck. They all have two doors per side per carriage, with a vestibule at each end at platform height. Well-known examples of these trains are the Tangara and Millennium trains.
In intermodal freight service, many modern types of container cars are designed to accommodate "double-stacking."
Cable Car (Aerial Tramway)
Main article: Aerial tramway
The double-deck Vanoise Express cable car carries 200 people in each cabin at a height of 380 m (1250') over the Ponturin gorge.
Tram
There are also double-deck trams. Hong Kong Tramways is the only tram company that operates double-deck trams exclusively. As with the buses and trolleybuses, double-deck versions are almost twice as tall as the others.
Until the 1950s double-deck trams were very common in the United Kingdom. Some can still be seen at the National Tramway Museum.
They are also in some places, aimed at tourists, e.g in Blackpool.
Bridge
The term double-decker is also used for bridges with two road levels, for example the San Francisco-Oakland Bay Bridge. Tsing Ma Bridge and Kap Shui Mun Bridge have six lanes on the upper decks. On the lower decks there are two lanes and a pair of tracks for trains (the MTR metro).
Tunnel
Some tunnels are double-deck, for example the Eastern Harbour Crossing in Hong Kong, where roads and rails (the MTR metro) occupy different decks of the tunnel.
Elevator
A double-deck elevator is an elevator with two elevator cars attached on top of each other. This increases passenger capacity while occupying less building core space.
Other Meanings
A "double-decker", in the American party scene, can also refer to having a bowel movement into the top tank on a toilet. This often proves quite humorous for the host or hostess, who normally do not realize the act has taken place until the following morning.