Dual-mode bus
Encyclopedia
Bus
A bus is a road vehicle designed to carry passengers. Buses can have a capacity as high as 300 passengers. The most common type of bus is the single-decker bus, with larger loads carried by double-decker buses and articulated buses, and smaller loads carried by midibuses and minibuses; coaches are...
that can run independently on power from two different sources, typically electricity from overhead lines
Overhead lines
Overhead lines or overhead wires are used to transmit electrical energy to trams, trolleybuses or trains at a distance from the energy supply point...
(in a similar way to trolleybus
Trolleybus
A trolleybus is an electric bus that draws its electricity from overhead wires using spring-loaded trolley poles. Two wires and poles are required to complete the electrical circuit...
es) or batteries, alternated with conventional fossil fuel
Fossil fuel
Fossil fuels are fuels formed by natural processes such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years...
(generally diesel fuel).
In contrast to other hybrid buses, dual-mode buses can run forever exclusively on their electric power source (wires). Several of the examples listed below involve the use of dual-mode buses to travel through a tunnel on electric overhead power.
Many modern trolleybuses are equipped with auxiliary propulsion systems, either using a small diesel engine
Diesel engine
A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...
or battery power, allowing movement away from the overhead wires, called "off-wire" movement, but such vehicles are generally not considered to be dual-mode buses if their off-wire capability is very limited. Examples include the fleet of about 300 trolleybuses in San Francisco and the trolleybuses used on a 2005-opened system in Rome
Rome
Rome is the capital of Italy and the country's largest and most populated city and comune, with over 2.7 million residents in . The city is located in the central-western portion of the Italian Peninsula, on the Tiber River within the Lazio region of Italy.Rome's history spans two and a half...
, Italy, which are capable of running on battery power only for short distances or short periods of time before needing recharging. The Rome vehicles are powered from overhead trolley wires over most of the 11.5-km route and only use battery power on the 500-metre section closest to the city centre.
Examples
- Bergen, Norway features dual-mode MAN-Neoplan buses in the Bergen trolleybusBergen trolleybusThe Bergen trolleybus system serves the city of Bergen, Norway. It is the only trolleybus system still in operation in Norway.The system opened on February 24, 1950, as the Bergen Tramway was gradually closed and some of the tramway lines were transferred to trolleybus operation...
system - BostonMBTA BusThe Massachusetts Bay Transportation Authority operates a large number of bus lines in the greater Boston area. Some routes are for transport within the city; others bring passengers from surrounding areas to stops on the rail lines of the MBTA.The MBTA also operates bus rapid transit service; see...
, Massachusetts, USA installed dual-mode Neoplan buses on the Waterfront portion of its Silver LineSilver Line (MBTA)The Silver Line is the only bus rapid transit line currently operated by the Massachusetts Bay Transportation Authority . It operates in two sections; the first runs from Dudley Square in Roxbury to downtown Boston, Massachusetts and South Station, mostly via Washington Street, with buses...
in 2005. Electric power is required in the exclusive right of way that runs in a tunnel under Fort Point ChannelFort Point ChannelFort Point Channel is a maritime channel separating South Boston from downtown Boston, Massachusetts, feeding into Boston Harbor. The south part of it has been gradually filled in for use by the South Bay rail yard and several highways...
to South StationSouth StationSouth Station, New England's second-largest transportation center , located at the intersection of Atlantic Avenue and Summer Street in Dewey Square, Boston, Massachusetts, is the largest train station and intercity bus terminal in Greater Boston, a prominent train station in the northeastern...
; dieselDiesel engineA diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...
power is used to run on city streets and highways, including the Ted Williams TunnelTed Williams TunnelThe Ted Williams Tunnel, also known as the Williams Tunnel, is the name of the third highway tunnel under Boston Harbor in Boston, Massachusetts, the Sumner and Callahan Tunnels being the other two...
to Logan Airport - Castellón de la PlanaCastellón de la PlanaCastellón de la Plana or Castelló de la Plana is the capital city of the province of Castelló, in the Valencian Community, Spain, in the east of the Iberian Peninsula, on the Costa del Azahar by the Mediterranean Sea...
, Spain installed a new trolleybus line that went into operation 25 June 2008. The IrisbusIrisbusIrisbus is a bus manufacturer which was formed through the merger of the bus and coach divisions of Fiat Industrial, Iveco and Renault in January 1999 and Ikarus Bus in late 1999...
Civis vehicles are optically guided and are capable of switching to diesel engine power for turning in front of the Parque Ribalta. - Seattle, Washington, USA used 236 dual-mode Breda ETB buses in its downtown bus tunnel from 1990 until late 2004, when the fleet of dual-mode buses were retired, except for 59 converted to electric-onlyTrolleybusA trolleybus is an electric bus that draws its electricity from overhead wires using spring-loaded trolley poles. Two wires and poles are required to complete the electrical circuit...
service and were replaced in the tunnel by hybrid diesel-electric busesHybrid electric busA hybrid electric bus combines a conventional internal combustion engine propulsion system with an electric propulsion system. These type of buses normally use a diesel-electric powertrain and are also known as hybrid diesel-electric buses....
.
See also
- Diesel-electric transmission
- Dual-mode vehicleDual-mode vehicleA dual-mode vehicle is a vehicle that can run on conventional road surfaces or a dedicated track known as a "guideway". Dual-mode vehicles are commonly electrically powered and run in dual-mode for power too, using batteries for short distance and low speeds, and track-fed power for longer...
- Electric busElectric busAn electric bus is a bus powered by electricity.There are two main electric bus categories:* Non-autonomous electric buses:**The trolleybus is a type of electric bus powered by two overhead electric wires, with electricity being drawn from one wire and returned via the other wire, using two...
- List of buses