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Double Decker Buses
Overview & Historical Background
Double-decker buses have been in use all around the world for
many purposes including mass
transit and touring. The double-decker buses are first developed
as early as the late 1800s. Over
thousands of double-decker buses are used as mass transit in the
UK and the rest of Europe, and Asia. The
US also has a history of use with double-decker buses. New York
City had been using the double-decker
buses for transit as early as 1912 until 1950s, and the open-top
style double-decker buses were the icons
of Fifth Avenue at the time. However, use of double-decker buses
did not regain interest after the 1950s
for more than 40 years, with few exceptions, until the 1990s
when BC Transit of Canada decides use
double-decker buses in Victoria. With hundreds of double-decker
buses in locations like Victoria and Las
Vegas, the double-decker buses now see growing interest in
possibly being the choice for many other
cities in North America.
Technologies
Typical dimensions for a double-decker bus are from 40-45 ft. in
length, 14 ft. tall, and 7.5-8.8 ft.
in width. Variations of the double-decker buses are closed top,
open top and double decker articulated
buses. Capacity for the typical double-decker bus ranges from
80-87 passengers. Engines used for double-
decker buses are mostly diesel engines. Other engines are CNG
propellers and hybrid diesel-electric
engines.
Advantages, Disadvantages, Barriers
Double-decker buses offer a few advantages over conventional
buses and articulated buses. They
have a higher capacity than conventional buses and take up less
road space than articulated buses. In
times of traffic congestion and limited road space, a higher
capacity within limited space can be very
important. In addition, passengers may appreciate higher and
unobstructed views when seating on the top
deck, leading to more preference towards double-decker
buses.
On the other hand, there are a number of disadvantages with
double-decker buses. First, there
may be restrictions in routes due to the vertical height of the
buses, limiting the route design process. The
design of the buses requires that all passengers on the top deck
must be seated for safety reasons, thus
limiting the total capacity of the bus. With higher capacity
comes with increased loading and unloading.
The buses will require a staircase to connect the decks, which
are not accessible for passengers with
physical disabilities and can deter passengers from climbing up
the stairs. More frontal area of the buses
means that there is more air resistance when traveling. Combined
with a higher center of gravity from the
height, double-decker buses operating in winter conditions and
high winds can be an important issue of
concern.The 2008 TCRP report on double-decker buses show that
the issue with vertical clearance can be
resolved with modifications in infrastructure given the
conditions of most roads in the US. In addition, a
review of regulations reveals that double-decker buses satisfy
the height limits of 21 states.
A possible barrier to obtaining double-decker buses in the US is
the Buy America Act, which,
according to the Department of Transportation, dictates that
transportation infrastructure projects are all
constructed with products made in the US. Major manufacturers of
high quality and mass number of
double-decker buses are located in Europe such as Alexander
Dennis and AEC of Leyland Motors in the
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UK and Van Hool in Belgium. However, the Enviro500 model from
Alexander Dennis is assembled in
the US and is compliant with Buy America, indicating that it is
possible to have international brands
operate within the US to ensure compliance with the Buy America
Act.
Economic Aspects
Based on the TCRP report, the cost of a typical double-decker
bus from Alexander Dennis with
capacity of 81 costs $600,000 while the cost an articulated
double-decker from Van Hool is in the low
600 thousands as of January 2007. Other sources suggest that a
double-decker bus can cost around
$500,000, which leads to the assumption that a typical
double-decker bus has a cost that ranges from
$500,000-$650,000. Based on the Transport for New South Wales
specifications of its new set of
double-deckers, each bus is expected to last up to 25 years,
more than the expected useful life of TCAT
current buses.
Another major cost to consider for double-decker buses is the
cost to modify facilities and
infrastructure. Removal of overhead obstructions, larger door
openings, portable lifts purchases,
modifications to garage and washing facilities are some extra
costs with double-decker buses. The
TCRPs sample modification cost calculation from a bus agency
sums up to be around $700,000.
Environmental Impacts
Transport for Londons (TfL) new set of iconic red AECs
Routemaster double deckers is
reported to have a fuel efficiency of 6.1 mpg for hybrid buses
and 5.3 mpg for diesel buses.
Measurements on eight prototypes of the new Routemasters for
eight months show a significant
improvement in bus emissions: 2.048g/km of nitrogen oxide,
690.23 g/km of CO2, and 0.012 g/km of
particulate matter. The levels of nitrogen oxide and particulate
matter are 75% less than that of the fleet
average of hybrid and diesel double-decker buses, while the
level of CO2emission is less than half. (bbc)
Applicability to Ithaca
Double-decker buses can certainly be considered for serving the
Ithaca and Tompkins County
area. The extra capacity can prove to be useful in satisfying
the demand level during rush hours. In
addition, the extra height of the buses should not prove to be
prohibitive because there are minor road
obstructions within the areas of service, especially those that
had seen high demand. It is important,
though, to note the severe winter conditions and the steepness
of roads in the Tompkins County that may
have affected the safety factor of using double-decker
buses.
