The history of 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 was little progress in Europe, although separate experiments were conducted in the USA. The next development was when Lombard Gérin operated an experimental line at the Paris Exhibition of 1900 after four years of trials. Max Schiemann made the biggest step when on 10 July 1901 the world's first passenger-carrying trolleybus operated at Bielathal (near Dresden) in Germany. Schiemann built and operated the Bielathal 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 the Bielathal system only operated until 1904, Schiemann had developed what is now the standard trolleybus current collection system. In the early days, however, there were a few different methods of current collection. The Cedes-Stoll system, designed by Carl Stoll, 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 operate passenger-carrying trolleybuses in the UK on 20 June 1911. 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 was responsible for turning the "trackless tram" into the trolleybus. There were 50 trolleybus operations in the UK in total, 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 short-lived Stockport operation used the Lloyd-Kölher system and Keighley used the Cedes-Stoll system.
In the United States, some cities, led by the Brooklyn-Manhattan Transit Corporation (BMT—New York), subscribed to the all-four concept of using buses, trolleybuses, trams (in U.S. called streetcars or trolleys) and rapid transit subway and/or elevated lines (metros), as appropriate, for routes ranging from 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. Although the BMT in Brooklyn built only one trolleybus line, other cities, notably San Francisco, California and Philadelphia, Pennsylvania, built larger systems and still maintain "all-four". If one includes cable cars as another mode, San Francisco could be called "all-five," as its cable cars provide general transportation while also serving as a popular tourist attraction and the only moving National Historic Landmark in the United States.
A number of trolleybus lines in the United States came into existence when a tracked trolley/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, has now been changed to a trolleybus scheme to cut costs.
Trolleybuses are advantageous on hilly routes, as electric power is more effective than diesel for climbing steep hills. Unlike combustion engines, electric motors draw power from a central plant and can be overloaded for several minutes without damage. San Francisco and Seattle, USA, both hilly, use trolleybuses partly for this reason, another being improved air quality. Given this acceleration and braking performance, trolleybuses easily outperform diesel buses on flat stretches as well.
Trolleybuses' rubber tires have better adhesion than streetcars' steel wheels on steel rails, giving them better hill climbing and braking. Unlike rail vehicles (where side tracks are not available), an out-of-service vehicle can be removed to the side of the road and its trolleys disconnected, allowing vehicles to pass. Additionally, because they are not tracked, trolleybuses can pull over to the curb as a diesel bus does, eliminating boarding islands in the street.
Philadelphia has operated trolleybuses (known regionally as trackless trolleys) in the past, and the city's SEPTA system has ordered a new fleet to restore trackless trolley service in 2008 to three of its five previous routes.
Like other electric vehicles, trolleybuses are more environmentally friendly than fossil-fuel or hydrocarbon-based vehicles (gasoline, diesel, alcohol, etc.). However the power is not free, having to be produced at centralised power plants, with attendant transmission losses.
On the other hand, centrally-produced power is more efficient, not bound to a specific fuel source and more amenable to pollution control as a single-source supply than are individual vehicles with their own engines that exhaust noxious gases and particulates at street level. Moreover, some cities, like Calgary, Alberta, run their commuter light rail networks using wind energy, which is effectively emission-free once the turbines are built and installed. A further advantage of trolleybuses is that they can generate electric power from kinetic energy whilst braking, a process known as regenerative braking.
Also, unlike buses or trams, trolleybuses are almost silent, lacking the noise of a diesel engine or 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 quite a number of pedestrians falling victim to what was also known as "the Silent Death".
Trolleybuses are specially favoured in locations where electricity is abundant and cheap. Examples of this are the extensive trolleybus systems in Vancouver, British Columbia, Canada and Seattle, Washington, USA, both of which draw hydroelectric power from the Columbia River and other Pacific river systems. Seattle benefits doubly, with steep gradients near the Downtown waterfront and on Queen Anne, First, and Capitol Hills. San Francisco also operates its trolleybus system using hydro power from the city-owned Hetch Hetchy generating plant.
Trolleybuses are used extensively in large European cities such as Athens, Belgrade, Bratislava, Bucharest, Budapest, Coimbra, Kiev, Lyon, Milan, Minsk, Moscow, Napoli, Riga, Saint Petersburg, Sarajevo and Sofia as well as smaller ones such as Arnhem, Banská Bystrica, Bergen, Bobruysk, Brest (Belarus), Cagliari, Cluj-Napoca, Gdynia, Geneva, Ghent, Gomel, Grodno, Iaşi, Košice, Lausanne, Limoges, Lublin, Luzern, Mogilev, Nancy, Plovdiv, Prešov, Salzburg, Simferopol, Solingen, Szeged, Tallinn, Vilnius, Vitebsk, Vladivostok, Yalta and Zürich.
Cities, especially those built on hills, have chosen trolleybuses over diesel buses because the electric motor can produce much more torque than a diesel engine. Moreover, the electric motor can be temporarily "overpowered", that is, more than the normal power can be obtained for a short period of time, e.g. when climbing a steep hill. Also, realising the advantages of these zero-emission vehicles, some other European cities have started to expand their systems again. Other cities such as Lecce will introduce new trolleybus systems.
In Cambridge, Massachusetts, the trolleybus system has survived because of the situation at Harvard Station, which holds an underground tunnel that was once used for streetcars. Despite a willingness to use buses, the tunnel at the time required left-side doors, and had fume concerns. Now, buses do run in the tunnel. However, the trolleybuses remain due to popular support.
Some have suggested that the trolleybus will become obsolete in a future hydrogen economy. However, direct electric transmission, as used in trolleybuses, is far more efficient (by a factor of two or more) than conversion of energy into hydrogen, transportation and storage of the hydrogen and its conversion back into electricity by fuel cells.
China is experimenting with a new form of electric bus that runs without powerlines. This bus runs on power stored in large onboard supercapacitors, which are quickly recharged at bus stops. Prototypes were being tested in Shanghai in early 2005.
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. Dewirements sometimes occur, leaving the bus stranded without power, although these events are relatively rare on systems with well-maintained overhead wire, hangers, fittings and "contact shoes." With the introduction of hybrid designs the trolleybus is no longer tied to its overhead trolley wires. Increasingly systems, such as Muni in San Francisco, TransLink in Vancouver, as well as Beijing's trolleybus operator, have circumvented this problem by installing battery packs on their trolleybuses to allow them to drive short to considerably long distances away from the wires. Also Supercapacitors may be used to drive small distances without connections to the grid. Boston is using dual-mode buses on its new Silver Line that run on overhead electricity on a fixed right of way and then transition to city streets using diesel power. In Philadelphia, Pennsylvania, where five trolleybus lines (trackless trolley locally preferred) have been suspended for partial reconstruction, new trolleybuses on order will have the capacity to operate short distances off the overhead wires through the use of a small diesel engine. In Athens, Greece, which has an extensive trolleybus system, in 2003-04 all trolleybuses were replaced with new vehicles that are equipped with a diesel engine that enables them to run off-line for a considerable distance.
Limitations in the creation of power lines also limits the use of trolleybuses and further restrictions may also apply where taller vehicles may need to share the route, preventing the installation of overhead lines. Nevertheless, installation is faster and less expensive than a tramway system.
Trolleybuses can pass one another in regular service, if two separate sets of wires with a switch are provided, or if the buses are battery-equipped.
Trolleybuses generally are implemented only when they confer one of the advantages listed above, due to the high cost of their infrastructure compared to the diesel bus. With increasing diesel fuel costs and particlulate matter and NOx emissions problems in many cities, trolleybuses yet may be seen as the best suited relief for many cities, either as the primary transit mode or as a supplement to rapid transit and commuter rail networks.
While at one time many cities operated this mode of transport, it is relatively uncommon today in North America, though it is still a common form of transport in many European, Russian, Brazilian and Chinese cities, generally occupying the niche between street railways (trams) and diesel-powered buses.
Some trolleybus systems have been criticized for aesthetic reasons, with city residents complaining that the jumble of overhead wires was unsightly.
Multiple branches may be handled by installing more than one switch. For example, to provide straight-through, left-turn or right-turn branches at an intersection, one switch is installed some distance from the intersection to choose a line over the left-turn lane, and another switch is mounted close to the intersection to choose between straight through and a right turn. [This would be the arrangement in countries such as the US, where traffic directionality is right-handed; in left-handed traffic countries such as Britain and New Zealand, the switch some distance from the intersection would be used to access the right-turn lanes, and the switch close to the intersection would be for the left-turn fork instead.]
Three common types of switch exist: Power-on/Power-off (the picture of a switch above is of this type), Selectric, and Fahslabend.
A Power-on/Power-off switch is triggered if the trolleybus is drawing power from the overhead wires, usually by accelerating, when the poles pass over the contacts. (The contacts are lined up on the wires in this case.) If no power is drawn (ie. the bus 'coasts' through the switch) the switch does not activate. Some trolley buses, such as those in Vancouver, British Columbia have a 'power-coast' toggle switch next to the driver which, dependent on what the driver desires, either causes the bus to draw power or completely halts all power draw from the overhead wires. This allows the driver to activate a switch by hand and allows a switch to be selected in situations which would otherwise be impossible, such as activating a switch while braking, or accelerating through a switch without activating it.
A Selectric switch has a similar design, but the contacts on the wires are not lined up but skewed, often at a 45-degree angle. This skew means that a bus going straight through will not trigger the switch, but a bus attempting a sharp turn (usually a right turn in countries with right-handed traffic) will cause its poles to meet the wires in a matching skew with one pole ahead of the other, which will trigger the switch.
For a Fahslabend switch, the bus's turn indicator (or a separate driver-controlled switch) causes a coded radio signal to be sent from a transmitter mounted on the bus (often attached to one of the trolley poles). The corresponding receiver is attached to the switch directly, and will cause 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). As a result, some cities operating trolleybuses have replaced other trolleybus switch types with this type of switch.
The first operational trolleybus service was introduced in 1933 in Moscow. In Soviet cities with underground metropolitan railways, trolleybus systems were intended to replace tramcars. In reality such plans were partially performed in the 1950s rather than in the 1930s. The first Soviet-made passenger trolleybus LK-1 was named after Politburo member Lazar Kaganovich. It was a dangerous and unreliable vehicle, quickly replaced by more advanced YaTB vehicles. These cars, both passenger and cargo, were the mainstay of the Soviet trolley fleet before the World War II. At this time new trolleybus systems were opened in Leningrad, Kiev, and a few other major Soviet cities.
During World War II, new trolleybus systems were opened in the Soviet Union. The need for mass transit in cities away from the front was urgent, but construction of tram lines was too expensive and time-consuming. Buses were largely mobilized to the Red Army as staff and medical vehicles. The remains of the bus fleet quickly stalled due to fuel shortages. The trolleybuses proved a good solution. Some vehicles, wires and other equipment were evacuated from Moscow in 1941; these materials were used for erecting new lines and systems in other cities. In the front-line city of Leningrad, trolleybus service ceased operations in November 1941 and was not restored until the end of the war. City trams were relaunched in April 1942 and performed without interruption under siege conditions. This restored Soviet plans of mass transit development in the form of co-existence of subways, trams, and trolleys.
The postwar period saw an explosion of development and expansion of trolleybus systems in the Soviet Union. Many cities and towns introduced passenger and cargo trolleybus services, sometimes interfering with tram operations. One of the most notable of these new trolleybus systems was the Crimean Trolleybus, currently the world's longest trolleybus line. Production at the time was limited to the monopoly Zavod imeni Uritskogo (ZiU, named after Moisei Uritsky). It produced thousands of MTB-82, ZiU-5, and ZiU-9 passenger trolleybuses for domestic purposes and for export. ZiU-5s and ZiU-9s were sold to Greece, Colombia, Argentina and Eastern Bloc countries. Three ZiU-9 cars were on loan in 1973 for testing purposes in Helsinki, Finland.
The collapse of the Soviet Union led to insufficient funding for many municipal trolleybus systems, but they proved more resilient than municipal tram or bus operations. There is only one closed trolleybus system in Shakhty within the area of modern Russia (whose operations ceased in October 2007). The suspended trolleybus operations from October 2006 in Archangelsk were reactivated in December 2007. The trolleybus system in Grozny was completely destroyed in the First Chechen War. Reconstruction is in planning. There is also one system with uncertain futures, in Voronezh. In other cities the development of trolleybus passenger services continues. Two new systems were introduced in Moscow suburbs Khimki and Vidnoe in the second half of the 1990s. ZiU, now named Trolza, has lost its monopoly in producing trolley vehicles. Today a number of domestic factories offer trolleybuses for the Russian market.
In Brazil, trolleybuses are currently in use only in Santos and in two systems in São Paulo: SPTrans, at the central and eastern region, and EMTU, at the suburbs and the cities of Santo André, São Bernardo do Campo, Mauá and Diadema. In São Paulo, two trolleybuses are preserved and exhibited at the SPTrans (São Paulo Transportation Authority) Museum Gaetano Ferrola. Another five trolleybuses built by CMTC and Villares between 1958 and 1965 are awaiting restoration in the SPTrans garage at Santa Rita. An original trolleybus built in the United States by ACF Brill in 1948 was restored in 1999 and currently can be seen riding in special celebrations, as occurred in the city's 454-year anniversary celebration on 25 January 2008.
Valparaíso, one of the largest cities of Chile and with a historic quarter declared a world heritage site by UNESCO, has the only trolley-bus service still working in that country, managed by a private company, Trolebuses de Chile S.A. (formerly Empresa de Transportes Colectivos Eléctricos). The available routes have the 8- prefix on Valparaíso's new metropolitan mass transit system (By now, just route 801 and 802). The fleet is a mix of old German, American, Swiss, and Chinese machines, making an attractive appeal for tourism. The most famous machines are the oldest Pullman Standard machines still in service in the world. (They were declared national monuments and still can be found working in the streets). The company has faced fierce competition from other non-electric bus lines, and almost faced bankruptcy several times in the past; however, many Valparaíso inhabitants feel an emotional link to the service, and tend to vigorously defend the maintenance of this privately funded company.
In Tampere trolleybus operations begun in 1948 and ended in 1976. At most extensive seven trolleybus lines were trafficked in the city. Following the end of trolleybus operations, two trolleybuses were preserved in the collection of Tampereen kaupungin liikennelaitos. In Helsinki a single trolleybus line was operated 1949–1974. An attempt to restore trolleybus traffic in Helsinki was made in the late 1970s; this resulted in the acquisition of a prototype trolleybus that was used between 1979 and 1985. Three Helsinki trolleybuses have been preserved. Of these, number 605 is on display at the Helsinki tram museum.
These cities do particularly increase this kind of transport, among them Lyon use Cristalis trolleybuses to build a "strong network" at small cost.
Preserved examples are kept at the Musée des Transports (AMTUIR) in Colombes.
Ex-Chicago trolleybuses dating from 1951-52 are being used in Guadalajara as of 2008.
Trolleybuses run in Bucharest, Cluj, Timisoara, Sibiu, Baia Mare, Piatra Neamt, Galati, Ploiesti, Constanta, Medias and Brasov. One "DAC 117 E" (1987) is preserved by the TRANSIRA Association.
In Lausanne, the Association Retrobus preserves old trolleybuses (from 1932) and enables them to circulate in town, especially on summer weekends.
The world's largest collection of preserved trolleybuses is at The Trolleybus Museum at Sandtoft in England. Examples are also preserved at the East Anglia Transport Museum and the Black Country Living Museum in England. The Bradford Trolleybus Association is currently restoring a Bradford Trolleybus 758, the last rear entrance trolleybus in Britain, which is kept at Sandtoft. The last trolleybuses in the United Kingdom ran in Bradford in 1972.