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"Trackless trolley" redirects here. For the non-electric buses that resemble historic streetcars, see Tourist trolley.
Busscar trolleybus in São Paulo, Brazil
Video of a trolleybus in Ghent, Belgium
Solaris trolleybus in Landskrona, Sweden
The "Elektromote", the world's first trolleybus,[citation needed] in Berlin, Germany, 1882
A trolleybus in Qingdao, China

A trolleybus (also known as trolley bus, trolley coach, trackless trolley, trackless tram [in early years][1] or trolley[2][3][4]) is an electric bus that draws its electricity from overhead wires (generally suspended from roadside posts) using spring-loaded trolley poles. Two wires and poles are required to complete the electrical circuit. This differs from a tram or streetcar, which normally uses the track as the return part of the electrical path and therefore needs only one wire and one pole (or pantograph). They also are distinct from other kinds of electric buses, which usually rely on batteries.

Currently, around 300 trolleybus systems are in operation, in cities and towns in 43 countries.[5] Altogether, more than 800 trolleybus systems have existed, but not more than about 400 concurrently.[6]


A double-deck trolleybus in Reading, England, 1966
An MBTA (Boston) low-floor trackless trolley near Harvard Square, Cambridge, USA. The "offside" door (on the left-hand side of the bus, despite the right-hand traffic) is peculiar to buses using the Harvard Square station in Cambridge

The trolleybus dates back to 29 April 1882, when Dr. Ernst Werner von Siemens ran his "Elektromote" in a Berlin suburb. This experimental demonstration continued until 13 June 1882, after which there were few developments in Europe, although separate experiments were conducted in the USA. In 1899, another vehicle which could run either on or off rails was demonstrated in Berlin.[7] The next development was when Lombard Gérin operated an experimental line at the Paris Exhibition of 1900 after four years of trials, connecting the Exhibition with the Porte de Vincennes.[7] Max Schiemann took the biggest step when on 10 July 1901 the world's first passenger-carrying trolleybus operated at Bielatal (Biela Valley, near Dresden), in Germany. Schiemann built and operated the Bielatal system, and is credited with developing the under-running trolley current collection system, with two horizontally parallel overhead wires and rigid trolleypoles spring-loaded to hold them up to the wires. Although this system operated only until 1904, Schiemann had developed what is now the standard trolleybus current collection system. In the early days there were a few other methods of current collection. The Cédès-Stoll (Mercédès-Électrique-Stoll) system was operated near Dresden between 1902 and 1904, and in Vienna. The Lloyd-Köhler or Bremen system was tried out in Bremen, and the Filovia was demonstrated near Milan.

Leeds and Bradford became the first cities to put trolleybuses into service in Great Britain on 20 June 1911.[7] Bradford was also the last to operate trolleybuses in the UK, the system closing on 26 March 1972. The last rear-entrance trolleybus in Britain was also in Bradford and is now owned by the Bradford Trolleybus Association. Birmingham was the first to replace a tram route with trolleybuses, while Wolverhampton, under the direction of Charles Owen Silvers, became world-famous for its trolleybus designs.[7] There were 50 trolleybus systems in the UK, London's being the largest. By the time trolleybuses arrived in Britain in 1911, the Schiemann system was well established and was the most common, although the Cédès-Stoll (Mercédès-Électrique-Stoll) system was tried in West Ham (in 1912) and in Keighley (in 1913).[7][8]

In the U.S.A., some cities, led by the Brooklyn-Manhattan Transit Corporation (BMT—New York), subscribed to the all-four concept of using buses, trolleybuses, trams (in US called streetcars or trolleys) and rapid transit subway and/or elevated lines (metros), as appropriate, for routes ranging from the lightly used to the heaviest trunk line. Buses and trolleybuses in particular were seen as entry systems that could later be upgraded to rail as appropriate. In a similar fashion, many cities in Britain originally viewed trolleybus routes as extensions to tram (streetcar) routes where the cost of constructing or restoring track could not be justified at the time, though this attitude changed markedly (to viewing them as outright replacements for tram routes) in the years after 1918.[7] Although the BMT in Brooklyn built only one trolleybus line, other cities, notably San Francisco (California), and Philadelphia (Pennsylvania), built larger systems and apparently still maintain an "all-four" approach to the current day.[citation needed] Some trolleybus lines in the United States (and in Britain, as noted above) came into existence when a trolley or tram route did not have sufficient ridership to warrant track maintenance or reconstruction. In a similar manner, a proposed tram scheme in Leeds, United Kingdom, was changed to a trolleybus scheme to cut costs.[9]

Trolleybuses are uncommon today in North America, but they remain common in many European countries as well as Russia and China, generally occupying a position in usage between street railways (trams) and diesel buses. Worldwide, around 300 cities or metropolitan areas are served by trolleybuses today.[5] (Further detail under Use and preservation, below.)

Trolleybuses are used extensively in large European cities, such as Athens, Belgrade, Bratislava, Bucharest, Budapest, Chisinau, Kiev, Lyon, Milan, Minsk, Moscow, Riga, Saint Petersburg, Sofia, Varna and Zurich, as well as smaller ones such as Arnhem, Bergen, Coimbra, Gdynia, Kaunas, Lausanne, Limoges, Luzern, Modena, Piatra Neamţ, Plzeň, Prešov, Salzburg, Solingen, Szeged, Tallinn, Târgu Jiu and Yalta. See also Trolleybus usage by country.

Transit authorities in some cities have reduced or discontinued their use of trolleybuses in recent years, while others, wanting to add or expand use of zero-emission vehicles in an urban environment, have opened new systems or are planning new systems. For example, Lecce, Italy, opened a new trolleybus system in 2012, and new systems are planned in Leeds and Montréal, among other places.


  1. Overhead line (overhead wires)
  2. Destination or route sign
  3. Rear view mirror
  4. Headlights
  5. Boarding (entry) doors
  6. Direction (turning) wheels
  7. Exit doors
  8. Traction wheels
  9. Decorative elements
  10. Retractors/retrievers
  11. Pole rope
  12. Contact shoes
  13. Trolley poles (power collector)
  14. Pole storage hooks
  15. Trolley pole base and fairing/shroud
  16. Bus Number


A San Francisco Muni trolleybus climbing Nob Hill
Irisbus Cristalis trolleybus in Limoges, France

Trolleybuses are advantageous on hilly routes, as electric motors are more effective than diesel engines in providing torque at start-up, an advantage for climbing steep hills. Unlike combustion engines, electric motors draw power from a central plant and can be overloaded for short periods without damage. San Francisco and Seattle, both hilly American cities, use trolleybuses partly for this reason, another being improved air quality. Given their acceleration and braking performance, trolleybuses can outperform diesel buses on flat stretches as well.

Trolleybuses' rubber tyres have better adhesion than trams' steel wheels on steel rails, giving them better hill-climbing capability and braking. Unlike rail vehicles (where side tracks are not available), an out-of-service vehicle can be moved to the side of the road and its trolley poles lowered, allowing other trolleybuses to pass. Additionally, because they are not confined to tracks, trolleybuses can pull over to the curb as a diesel bus does, eliminating boarding islands in the middle of the street.

Like other electric vehicles, trolleybuses are more environmentally friendly in the city than fossil-fuel or hydrocarbon-based vehicles (petrol/gasoline, diesel, alcohol, etc.). Although the power is not free, having to be produced at centralised power plants with attendant transmission losses, it is produced more efficiently. Further, it is not bound to a specific fuel source and is more amenable to pollution control as a point source supply than are individual vehicles with their own engines exhausting noxious gases and particulates at street level. Moreover, some cities, like Calgary, Alberta, run their light rail networks using wind energy,[10] which is effectively emission-free once the turbines are built and installed. Other cities, Vancouver, B.C., for instance, use hydroelectricity. A further advantage of trolleybuses is that they can generate electricity from kinetic energy while braking, a process known as regenerative braking. However, for regenerative braking to work as such, there must be another bus on the same circuit that needs power, or a way to send the excess power back to the commercial electric power system. Otherwise the braking power must be dissipated in resistance grids on the bus, when it is called "dynamic braking". There are alternatives, such as batteries or flywheels on the bus or at the bus power station, but they add to the investment, complexity and maintenance expenses.

Unlike trams or gasoline and diesel buses, trolleybuses are almost silent, lacking the noise of an engine or of wheels on rails. Such noise as there is tends to emanate from auxiliary systems such as power steering pumps and air conditioning. Early trolleybuses without these systems were even quieter and, in the UK at least, were often referred to as the "Silent Service". The quietness did have its disadvantages though, with some pedestrians falling victim to what was also known as the "Silent Death" (in Britain) or "Whispering Death" (in Australia).

Trolleybuses are especially favoured where electricity is abundant and cheap. Examples are the extensive systems in Vancouver, Canada and Seattle, USA, both of which draw hydroelectric power from the Columbia River and other Pacific river systems. San Francisco operates its system using hydro power from the city-owned Hetch Hetchy generating plant.

As can be seen from examples in this article, electric (trolley) buses tend to be very long-lived as compared to internal combustion engine-powered buses. As the basic construction of buses has not changed much in the last fifty plus years, they can be upgraded such as when air conditioning was retrofitted to many trolleybuses when it became available. Wheelchair lifts are relatively simple to add; kneeling front suspension is a common feature of air suspension on the front axle in place of springs.

In Cambridge, Massachusetts, trackless trolleys survived because Harvard Station, where several bus lines terminate, is in a tunnel that was once used by streetcars. Although diesel buses do use the tunnel, there are limitations due to exhaust fumes. Also the trackless trolleys continue to have popular support.

Indicator for a wire switch[11]
Pole bases with springs and pneumatic pole lowering cylinders
Insulated poles, contact shoes, and pull–ropes


Re-routings, temporary or permanent, are not usually readily available outside of "downtown" areas where the buses may be re-routed via adjacent business area streets where other trolleybus routes operate. This problem was highlighted in Vancouver in July 2008,[12] when an explosion closed several roads in the city's downtown core. Because of the closure, trolleys were forced to detour several kilometers off their route in order to stay on the wires, leaving major portions of their routes unserved and service well off schedule. Also trolley buses have unique operating characteristics, such as trolley drivers having to slow down at turns and through switches in the overhead wire system.[SDOT 1]

Some trolleybus systems have been criticised for aesthetic reasons, with city residents complaining that the jumble of overhead wires was unsightly.[13] Intersections often have a "webbed ceiling" appearance, due to multiple crossing and converging sets of trolley wires.

Dewirements — when the trolley poles come off of the wires — sometimes occur, especially in areas subject to heavy snow. After a dewirement, trolleybuses not equipped with an auxiliary power unit (APU) are stranded without power. However, dewirements are relatively rare in modern systems with well-maintained overhead wires, hangers, fittings and "contact shoes". Trolleybuses are equipped with special insulated pole ropes which drivers use to reconnect the trolley poles with the overhead wires in case of dewirement. When approaching switches, trolleybuses usually must decelerate in order to avoid dewiring, and this deceleration can potentially add slightly to traffic congestion.

Trolleybuses cannot overtake one another in regular service unless two separate sets of wires with a switch are provided or the vehicles are equipped with off-wire capability, but the latter is an increasingly common feature of new trolleybuses.

Recent power developments[edit]


With the introduction of hybrid designs, trolleybuses are no longer tied to overhead wires. Since the 1980s, trolleybus systems in Muni in San Francisco, TransLink in Vancouver, and in Beijing, among others, have bought trolleybuses equipped with batteries to allow them to operate fairly long distances away from the wires. Supercapacitors can be also used to move buses short distances.

Trolleybuses can optionally be equipped either with limited off-wire capability—a small diesel engine or battery pack—for auxiliary or emergency use only, or full dual-mode capability. A simple auxiliary power unit can allow a trolleybus to get around a route blockage or can reduce the amount (or complexity) of overhead wiring needed at operating garages (depots). This capability has become increasingly common in newer trolleybuses, particularly in North America and Western Europe, where the vast majority of new trolleybuses delivered since the 1990s are fitted with at least limited off-wire capability. These have gradually replaced older trolleybuses which lacked such capability. In Philadelphia, new trolleybuses (known there as "trackless trolleys") that were placed in service by SEPTA in 2008 are equipped with small hybrid diesel-electric power units for operating short distances off-wire, instead of using a conventional diesel drive train or battery-only system for their off-wire movement.[14]


Other considerations[edit]


Being electric, trolleybuses are a lot quieter than diesel- or petrol-engined vehicles. While this is mainly seen as a benefit, it does also make it easier for unobservant pedestrians and other motorists to miss hearing a trolleybus when crossing a street and risk being struck. A speaker attached to the front of the vehicle can raise the noise to a desired "safe" level. This noise can be directed to pedestrians in front of the vehicle, as opposed to motor noise which typically comes from the rear of a bus and is more noticeable to bystanders than to pedestrians.


Wire switches[edit]

Trolleybus wire switch



Three common types of switches[15] exist: Power-on/Power-off (the picture of a switch above is of this type), Selectric, and Fahslabend.



For a Fahslabend switch, the trolleybus's turn indicator control (or a separate driver-controlled switch) causes a coded radio signal to be sent from a transmitter, often attached to a trolley pole. The receiver is attached to the switch and causes it to trigger if the correct code is received. This has the advantage that the driver does not need to be accelerating the bus (as with a Power-on/Power-off switch) or trying to make a sharp turn (as with a Selectric switch).



A ZiU-9 trolleybus in service in Piraeus, Greece, on the large Athens-area trolleybus system. The Russian-built ZiU-9 (also known as the ZiU-682), introduced in 1972, is the most numerous trolleybus model in history, with more than 45,000 built.[6]:114 In the 2000s it was effectively rendered obsolete by low-floor designs.

Since the invention of the mode, well over 200 different makers of trolleybuses have existed – mostly commercial manufacturers, but in some cases (particularly in China), trolleybuses have been built by the publicly owned trolleybus operating companies or authorities.[6]:91–125 Of the defunct or former trolleybus manufacturers, the largest producers – ones whose production totalled more than 1,000 units each – included the U.S. companies Brill (approx. 3,250 total), Pullman-Standard (2,007), and Marmon-Herrington (1,624); the English companies AEC (approx. 1,750), British United Traction (BUT) (1,573), Leyland (1,420) and Sunbeam (1,379); France's Vétra (more than 1,750); and the Italian builders Alfa Romeo (2,044) and Fiat (approx. 1,700).[6]

As of the 2010s, at least 30 trolleybus manufacturers exist. They include some companies that have been building trolleybuses for several decades, such as Škoda, Trolza (formerly Uritsky, or ZIU) and New Flyer, among others, along with several younger companies. Current trolleybus manufacturers in western and central Europe include Solaris, Van Hool and Hess, among others. In Mexico, trolleybus production ended when MASA, which had built more than 860 trolleybuses since 1979, was acquired in 1998 by Volvo. However, Dina, which is now that country's largest bus and truck manufacturer, began building trolleybuses in 2013.[17]:134

Transition to low-floor designs[edit]


In the United States, the Americans with Disabilities Act of 1990 required that all new transit vehicles placed into service after 1 July 1993 be accessible to persons in wheelchairs.[19] Some transit agencies had already begun to accommodate such passengers by purchasing buses with wheelchair lifts, and early examples of fleets of lift-equipped trolleybuses included 109 AM General trolleybuses built for the Seattle trolleybus system in 1979 and the retrofitting of lifts in 1983 to 64 Flyer E800s in the Dayton system's fleet.[20]:61

One of the NAW/Hess trolleybuses delivered to Geneva in 1992, which were among the first production-series low-floor trolleybuses anywhere

Trolleybuses in other countries continued to lack disabled access until the 1990s, when the first two low-floor trolleybus models were introduced, both built in 1991, a "Swisstrolley" demonstrator built by Switzerland's NAW/Hess and an N6020 demonstrator built by Neoplan.[21][22] The first production-series low-floor trolleybuses were built in 1992: 13 by NAW for the Geneva system and 10 Gräf & Stift for the Innsbruck system (de). By 1995, such vehicles were also being made by several other European manufacturers, including Skoda, Breda, Ikarus and Van Hool.[23] The first Solaris "Trollino" made its debut in early 2001.[24]:30 In the former Soviet Union countries, Belarus' Belkommunmash built its first low-floor trolleybus (model AKSM-333) in 1999,[25] and other manufacturers in the former Soviet countries joined the trend in the early 2000s.

The emergence of low-floor designs raised an unforeseen issue for some European trolleybus operators. The lifespan of a trolleybus is typically much longer than that of a motorbus, with 20–30 years being "not uncommon",[26] but with the 1990s trend moving strongly toward low-floor vehicles, some operators whose high-floor trolleybuses were only a few years old felt pressure to retire them at a much younger age, so as to replace them with low-floor trolleybuses.[26] Responses varied, with some systems keeping their high-floor fleets, and others retiring them early but, in many instances, selling them secondhand for continued use in countries where there was a demand for low-cost secondhand trolleybuses, in particular in Romania and Bulgaria. The Lausanne system dealt with this dilemma in the 1990s by purchasing new low-floor passenger trailers to be towed by its high-floor trolleybuses,[26] a choice later also made by Lucerne.


Outside Europe, 14 vehicles built by, and for, the Shanghai trolleybus system in mid-1999 were the first reported low-floor trolleybuses in Southeast Asia.[27] Wellington, New Zealand, took delivery of its first low-floor trolleybus in March 2003,[28] and by the end of 2009 had renewed its entire fleet with such vehicles.[29]

In the Americas, the first low-floor trolleybus was a Busscar vehicle supplied to the São Paulo EMTU system in 2001.[30] In North America, wheelchair lifts were again chosen[26] for disabled access in new trolleybuses delivered to San Francisco in 1992–94, to Dayton in 1996–1999, and to Seattle in 2001–2002, but the first low-floor trolleybus was built in 2003, with the first of 28 Neoplan vehicles for the Boston system.[30] Subsequently, the Vancouver system and the Philadelphia system have converted entirely to low-floor vehicles, and in 2013 the Seattle and Dayton systems both placed orders for their first low-floor trolleybuses. Outside São Paulo, almost all trolleybuses currently in service in Latin America are high-floor models built before 2000. However, in 2013, the first domestically manufactured low-floor trolleybuses were introduced in both Argentina and Mexico.[17]:134

With regard to non-passenger aspects of vehicle design, the transition from high-floor to low-floor has meant that some equipment previously placed under the floor has been moved to the roof.[19] Some transit operators have needed to modify their maintenance facilities to accommodate this change, a one-time expense.

Double-decker trolleybuses[edit]

The last trolleybus to operate in Northern Ireland was this double-decker shown travelling on the Shore Road, Belfast in 1968.


In 2001, Citybus (Hong Kong) converted a Dennis Dragon (#701) into a double-decker trolleybus,[31] and it was tested on a 300-metre track in Wong Chuk Hang in that year.[31] Hong Kong decided not to build a trolleybus system, and the testing of this prototype did not lead to any further production of vehicles.

Use and preservation[edit]

There are currently 300 cities or metropolitan areas where trolleybuses are operated,[5] and more than 500 additional trolleybus systems have existed in the past.[6] For an overview, by country, see Trolleybus usage by country, and for complete lists of trolleybus systems by location, with dates of opening and (where applicable) closure, see List of trolleybus systems and the related lists indexed there.

Of the systems existing as of 2012, the majority are located in Europe and Asia, including 85 in Russia and 43 in Ukraine.[5] However, there are eight systems existing in North America, nine in South America and one in Oceania (specifically in New Zealand).[5]

Trolleybuses have been preserved in most of the countries where they have operated. The United Kingdom has the largest number of preserved trolleybuses with more than 110, while the United States has around 70.[6] Most preserved vehicles are on static display only, but a few museums are equipped with a trolleybus line, allowing trolleybuses to operate for visitors. Museums with operational trolleybus routes include three in the UK – the Trolleybus Museum at Sandtoft, the East Anglia Transport Museum and the Black Country Living Museum – and three in the United States – the Illinois Railway Museum, the Seashore Trolley Museum and the Shore Line Trolley Museum[32] – but operation of trolleybuses does not necessarily occur on a regular schedule of dates at these museums.

See also[edit]


  3. ^ "Trolley service begins the next 60 years" (Press release). TransLink. August 16, 2008. Archived from the original on 19 July 2011. Retrieved 6 September 2012. 
  4. ^ Tan, Vinh (15 October 2009). "Take a ride down memory lane — or to see fall foliage — aboard a vintage transit bus". The Seattle Times. Retrieved 6 September 2012. 
  6. ^ a b c d e f g h Murray, Alan (2000). World Trolleybus Encyclopaedia. Yateley, Hampshire, UK: Trolleybooks. ISBN 0-904235-18-1.
  7. ^ a b c d e f Charles S. Dunbar, Buses, Trolleys and Trams, (Paul Hamlyn Ltd, 1967, no ISBN) p. 81 et seq.
  10. ^ Wind Energy Background[dead link]
  11. ^ G. Cebrat. "Greenfleet". Retrieved 2010-11-29. 
  12. ^ CBC news article: Retrieved 8 November 2010. Other reports stated that the (electrical) explosion did not affect power supply to the trolleybuses (only implied by this article).
  13. ^ Ashley Bruce. "Overhead". Retrieved 2010-11-29. 
  17. ^ a b Trolleybus Magazine No. 311 (September–October 2013).
  26. ^ a b c d "Low-floor or Long Life?" (November–December 1998). Trolleybus Magazine No. 222, p. 122. National Trolleybus Association (UK).
  1. ^ SDOT. "Electric Trolley Bus Fact Sheet". Seattle Department of Transportation. Retrieved 2012-03-29. 




  • Trackless, Bradford Trolleybus Association, quarterly
  • Trolleybus, British Trolleybus Society (UK), monthly

External links[edit]