Trolleybus


A trolleybus is an electric bus that draws power from dual overhead lines using spring-loaded or pneumatically raised trolley poles. Two wires, and two trolley poles, are required to complete the electrical circuit. This differs from a tram or streetcar, which normally uses the track as the return path, needing only one wire and one pole. They are also distinct from other kinds of electric buses, which usually rely on batteries. Power is most commonly supplied as 600-volt direct current in older systems and 750-volts in newer systems, but there are exceptions.
Currently, around 300 trolleybus systems are in operation, in cities and towns in 43 countries. Altogether, more than 800 trolleybus systems have existed, but not more than about 400 concurrently.

History

The trolleybus dates back to 29 April 1882, when Dr. Ernst Werner Siemens demonstrated his "Elektromote" in a Berlin suburb. This experiment continued until 13 June 1882, after which there were few developments in Europe, although separate experiments were conducted in the United States. In 1899, another vehicle which could run either on or off rails was demonstrated in Berlin. The next development was when Louis Lombard-Gérin operated an experimental line at the Paris Exhibition of 1900 after four years of trials, with a circular route around Lake Daumesnil that carried passengers. Routes followed in six places including Eberswalde and Fontainebleau. Max Schiemann on 10 July 1901 opened the world's fourth passenger-carrying trolleybus system, which operated at Bielatal, 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 many other methods of current collection. The Cédès-Stoll system was first operated near Dresden between 1902 and 1904, and 18 systems followed. The Lloyd-Köhler or Bremen system was tried out in Bremen with 5 further installations, and the Cantono-Frigerio system was used in Italy.
Throughout this period, trackless freight systems and electric canal boats were also built.
Leeds and Bradford became the first cities to put trolleybuses into service in Great Britain, on 20 June 1911. Supposedly, though it was opened on 20 June, the public was not admitted to the Bradford route until the 24th. Bradford was also the last city to operate trolleybuses in the UK; the system closed on 26 March 1972. The last rear-entrance trolleybus in service in Britain was also in Bradford and is now owned by the Bradford Trolleybus Association. Birmingham was the first UK city to replace a tram route with trolleybuses, while Wolverhampton, under the direction of Charles Owen Silvers, became world-famous for its trolleybus designs. 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 system was tried in West Ham and in Keighley.
Smaller trackless trolley systems were built in the US early as well. The first non-experimental system was a seasonal municipal line installed near Nantasket Beach in 1904; the first year-round commercial line was built to open a hilly property to development just outside Los Angeles in 1910. The trackless trolley was often seen as an interim step, leading to streetcars. In the US, some systems subscribed to the all-four concept of using buses, trolleybuses, streetcars , and rapid transit subway and/or elevated lines, 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 routes where the cost of constructing or restoring track could not be justified at the time, though this attitude changed markedly in the years after 1918. Trackless trolleys were the dominant form of new post-World War I electric traction, with extensive systems in among others, Los Angeles, Chicago, Boston, Rhode Island, and Atlanta; San Francisco and Philadelphia still maintain an "all-four" fleet.
Some trolleybus lines in the United States 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.
File:СМЕ из ЗиУ-9 в Ленинграде.jpg|thumb|250px|MU ZiU-9 in Leningrad, Soviet Union, 1987
Trolleybuses are uncommon today in North America, but their use is widespread in Europe, Asia, South America and in countries which were part of the Soviet Union. Generally trolleybuses occupy a position in usage between street railways and motorbuses. Worldwide, around 300 cities or metropolitan areas on 5 continents are served by trolleybuses.File:WYMT 34980 leaving Wuyang Community.jpg|thumb|Coal mines also operate trolleybus networks to serve workers. Wuyang Coal Mine in Xiangyuan, Changzhi, Shanxi has the last remaining mine trolleybus system in China.
This mode of transport operates in large cities, such as Belgrade, Lyon, Pyongyang, São Paulo, Seattle, Sofia, St. Petersburg, and Zurich, as well as in smaller ones such as Dayton, Gdynia, Lausanne, Limoges, Modena, and Salzburg. As of 2020, Kyiv has the largest trolleybus system in the world in terms of route length, while Minsk, has the largest system in terms of number of routes. Sweden's Landskrona has the smallest system in terms of route length, while Czech Republic's Mariánské Lázně is the smallest city to be served by trolleybuses. Opened in 1914, the Shanghai trolleybus system is the oldest currently operating system in the world. With a length of 86 km, route #52 of Crimean Trolleybus is the longest trolleybus line in the world. See also Trolleybus usage by country.''
Transit authorities in some cities have reduced or discontinued the use of trolleybuses, 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, new systems opened in Lecce, Italy, in 2012; in Malatya, Turkey, in 2015; and in Marrakesh in 2017. Beijing and Shanghai have been expanding their respective systems, with Beijing growing to a 31-line system operated with a fleet of over 1,250 trolleybuses. In North Korea, the newest city to have a network is Manpo in December 2019. Since the year 2022, the city of Prague is constructing a new trolleybus system. Meanwhile, in 2023, plans for a trolleybus line in Berlin were scrapped in favour of a solution with battery-powered vehicles.

Vehicle design

Modern-design trolleybuses

Advantages

Comparison to trams

  • Cheaper infrastructureThe initial start up cost of trams is much higher, due to rail, signals, and other infrastructure. Trolleybuses can pull over to the curb like other buses, eliminating the need for special boarding stations or boarding islands in the middle of the street, thus stations can be moved as needed.
  • Better hill climbingTrolleybuses' rubber tyres have better adhesion than trams' steel wheels on steel rails, giving them better hill-climbing capability and braking.
  • Easier traffic avoidanceUnlike trams, an out-of-service vehicle can be moved to the side of the road and its trolley poles lowered. The ability to drive a substantial distance from the power wires allows trackless vehicles to avoid obstacles, although it also means a possibility that the vehicle may steer or skid far enough that the trolley pole can no longer reach the wire, stranding the vehicle. Trackless trolleys also are able to avoid collisions by manoeuvring around obstacles, similar to motor buses and other road vehicles, while trams can only change speed.
  • QuietnessTrolleybuses are generally quieter than trams.
  • Easier trainingThe control of trolleybuses is relatively similar to motorbuses; the potential operator pool for all buses is much larger than for trams.

    Comparison to motorbuses

Disadvantages

Comparison to trams

Note: As there are numerous variations of tram and light-rail technology, the disadvantages listed may be applicable only with a specific technology or design.
  • Like any bus, much less capacity than trams.
  • More control requiredTrolleybuses must be driven like motorbuses, requiring directional control by the driver.
  • Higher rolling resistanceRubber-tired vehicles generally have more rolling resistance than steel wheels, which decreases energy efficiency.
  • Less efficient use of right-of-wayLanes must be wider for unguided buses than for streetcars, since unguided buses can drift side-to-side. The use of guidance rail allows trams running in parallel lanes to pass closer together than drivers could safely steer.
  • Difficulties with platform loadingImplementation of level platform loading with minimal gap, either at design stage or afterwards, is easier and cheaper to implement with rail vehicles.
  • Wear of rubber tires leads to significant rubber pollution.

    Comparison to motorbuses

  • Difficult to re-routeWhen compared to motorbuses, trolleybuses have greater difficulties with temporary or permanent re-routings, wiring for which is 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, when an explosion closed several roads in the city's downtown core. Because of the closure, trolleys were forced to detour several miles off their route in order to stay on the wires, leaving major portions of their routes not in service and off-schedule.
  • AestheticsThe jumble of overhead wires may be seen as unsightly. Intersections often have a "webbed ceiling" appearance, due to multiple crossing and converging sets of trolley wires.
  • DewirementsTrolley poles sometimes come off the wire. 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. When approaching switches, trolleybuses usually must decelerate in order to avoid dewiring, and this deceleration can potentially add slightly to traffic congestion. In 1998, a dewirement in Shenyang on poorly maintained infrastructure killed 5 people and ultimately led to the destruction of the trolleybus network.
  • Unable to overtake other trolleybusesTrolleybuses 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, with the latter an increasingly common feature of new trolleybuses.
  • Higher capital cost of equipmentTrolleybuses are often long-lived equipment, with limited market demand. This generally leads to higher prices relative to internal combustion buses. The long equipment life may also complicate upgrades.
  • More training requiredDrivers must learn how to prevent dewiring, slowing down at turns and through switches in the overhead wire system, for example.
  • Overhead wires create obstructionTrolleybus systems employ overhead wires above the roads, often shared with other vehicles. The wires can restrict tall motor vehicles such as delivery trucks and double decker buses from using or crossing roads fitted with overhead wires, as such vehicles would hit the wires or pass dangerously close to them, risking damage and dangerous electrical faults. The wires also may impede positioning of overhead signage and create a hazard to activities such as road repairs using tall excavators or piling rigs, use of scaffolding, etc.