Double decker
From Wikipedia, the free encyclopedia
- For the chocolate bar, see Double Decker (chocolate bar)
A double-decker is a bus, aeroplane, train, tram, ferry or any public transit vehicle that has two levels for passengers, one deck above the other. The term can also refer to a sandwich with three layers of bread and two fillings; and to roads and bridges which have one roadway running above another.
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[edit] Bus
Double-decker buses are taller than other buses. They are extensively used in the United Kingdom, where perhaps the most famous was the London Routemaster, removed from normal service in December 2005 - they still operate on heritage routes. Elsewhere in Europe, double-deckers are used throughout the Dublin Bus network and some Bus Éireann routes in Ireland, where they are making a comeback on Dublin's outer suburban routes (e.g. Dublin-Navan) and also the streets of Cork, Limerick, Galway and Waterford. They are a common sight in Berlin, where the BVG makes extensive use of them. Double-decker long-distance coaches are also in widespread use throughout Europe.
Most buses in Hong Kong and about half in Singapore are double-deckers as well. The only areas in North America that use double-decker buses for public transport are the western Canadian province of British Columbia and the United States city of Las Vegas. They are currently being tested in Ottawa on the express routes. The city of Davis, California, in the United States uses vintage double-decker buses for public transport run by Unitrans. Unitrans is affiliated with the University of California, Davis, and has run these buses since 1968. Davis, California is also home to the first vintage double-decker bus converted from diesel gasoline to run on CNG. On the Las Vegas Strip, The Deuce operates an all-duble decker fleet, and Citizens Area Transit also runs double deckers on two local routes. The city of Victoria, BC, Kelowna, BC and a couple of others use Dennis Tridents. A few are also used as tour buses, especially in New York. Double-deckers are have also been used in Mumbai since 1937.
In Brazil, where buses are sometimes the only interstate transport, some companies use double-decker buses, like those that Viação Cometa uses in the route between Campinas and Rio de Janeiro. Double-decker buses are in widespread use in India, remarkably in Mumbai, where they are operated by Brihanmumbai Electric Supply and Transport (BEST). Most of these buses are local derivatives of either Roadmaster or Leyland.
Double-deckers are not a good option for use outside urban areas and their use is being discouraged by transportation authorities all over the world. They do not really double the capacity, just add some numbers to the one served by single level buses.
Some double-decker buses have an open upper deck, with no roof and shallow sides. These are popular for sightseeing tours.
[edit] Airplane
Many early seaplane airliners, such as the Boeing 314 Clipper and Short Sandringham, had two decks for passengers. Following World War II, a double-decked derivative of the B-29 Superfortress called the Stratocruiser became popular with airlines around the world.
For years the only double-deck jet airliner in service was the Boeing 747, though the top deck is smaller than the main level. The new Airbus A380, however, has two decks extending the full length of the airplane.
[edit] Train
Because of the standard height of tunnels and overhead power wires, many double-deck trains set the bottom deck lower down, between the bogies. Usually the entrance doors are above the bogies, and there is only one deck at the entance area. 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, and from there seven steps up or four steps down. Some double-decker trains have their entrance doors on the lower level and no steps are needed to get to the lower deck.
Other double-deck cars do not have a full upper deck but have a gallery on each side, each with a row of single seats. An example is the bilevel cars provided and leased in the U.S. by Midwest Transportation & Development Corporation of Chicago. They are of a design proven in service and steadily refined since their introduction in the 1950s. These cars, known as "bilevel gallery cars", are among the most successful designs developed, and are currently in daily use in Chicago, San Francisco, and Montreal (Agence métropolitaine de transport). They provide high capacity (155 to 169 passengers each) and use standard, off-the-shelf components, without relying on proprietary, expensive and hard-to-get replacement parts. Chicago's commuter rail system Metra is currently receiving new versions of these cars and Caltrain, the San Francisco area commuter rail authority, has recently overhauled its fleet. NJ Transit has recently introduced bilevel trains in its fleet. One common model in the United States is the Bombardier BiLevel Coach.
Another advantage of bilevel gallery cars is the relatively low first step of the vestibule entrance to the car, which is 14 5/8" (371 mm) above the head of the rail. The advantage of this is that commuter rail operators do not have to spend scarce funds on building high-level platforms; a low-level platform is all that is necessary, at a far lower cost.
[edit] 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 in France.
[edit] Tram
There are also double-deck trams. Hong Kong Tramways is the only tram company that operates double-deck trams exclusively.
Double deckers also operate in Blackpool and Alexandria. Until the 1950s double-deck trams were common in the United Kingdom. Some can still be seen at the National Tramway Museum.
From 1910 to 1964, double-decker trams were in use in Mumbai.
[edit] Bridge
The term double-decker is also used for bridges, such as the San Francisco-Oakland Bay Bridge, with two road levels. Tsing Ma Bridge and Kap Shui Mun Bridge in Hong Kong have six lanes on their upper decks, and on their lower decks there are two lanes and a pair of tracks for MTR metro trains. Some double-decker bridges only use one level for street traffic; the Washington Avenue Bridge in Minneapolis reserves its lower level for automoblie traffic and its upper level for pedestrian and bicycle traffic (predominantly by students at the University of Minnesota).
Robert Stephenson's High Level Bridge in Newcastle upon Tyne, completed in 1849, is an early example of a double decker bridge. The upper level carries a railway across the River Tyne; the lower level is used for road traffic.
Another example is Craigavon Bridge in Derry, Northern Ireland.
[edit] 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.
The two major segments of the [[San Francisco-Oakland Bay Bridge (completed in 1936), are linked by a double deck tunnel, once the largest diameter tunnel in the world. At construction this was a combination bidirectional rail and truck pathway on the lower deck with automobiles above, now converted to one-way road vehicle traffic on each deck.
A recent double-decked tunnel with both decks for motor vehicles is the Fuxing Road Tunnel in Shanghai, China. Cars travel on the two-lane upper deck and heavier vehicles on the single-lane lower.
[edit] Double decker trailer
A double-decker trailer is a two-level trailer with living quarters in it, or "travel trailer". When traveling the trailer is only as high as a regular trailer, but when set up it increases in height to two full levels. Built by Jexcar and others, they are often used in motion picture production as portable dressing rooms.
[edit] Elevator
A double-deck elevator is an elevator with two elevator cars on top of each other. This increases passenger capacity while occupying less building core space.
[edit] Food-related meanings
Double Decker is a brand of chocolate bar from Cadbury UK.
The double decker sandwich is a common staple of restaurants all over the world, most notably the Club sandwich. Consisting of two layers of turkey, lettuce, tomato and various condiments sandwiched between three pieces of bread.
A common misconception among the general public is that a double decker sandwich is in fact a triple decker. This is a fallacy. The reason for this misnomer is simply due to the three pieces of bread.
[edit] See also
