A — 3: double-decker city buses are less common
B — 4: where perhaps the most famous was the London Routemaster
C — 2: use double-decker buses for public transport
D — 7: where buses are sometimes the only interstate transport
E — 5: their use is being discouraged by transportation authorities
F — 6: have an open upper deck
A double-decker bus is a bus that has two levels. While double-decker long-distance buses are in widespread use around the world, __double-decker city buses are less common__. Double-decker buses are popular in some European cities and in some parts of Asia, usually in former British colonies. Many towns around the world have a few that specialize in short sight-seeing tours for tourists because, as William Gladstone observed, «the way to see London is from the top of a ‘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 in Ireland, where they are making a comeback on Dublin’s outer suburban routes 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. Davis, California is also home to the first vintage double-decker bus converted from diesel gasoline to run on CNG. The city of Victoria, BC, the city of Vancouver, British Columbia, 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. Double-deckers are not a good option for use outside the towns (most roads in Brazil are in very poor condition), and __their use is being discouraged by transportation authorities__.
Double-decker buses are in widespread use in India in many of the major cities. Some double-decker buses __have an open upper deck__, with no roof and shallow sides. These are popular for sightseeing tours.