Trolleybus

A trolleybus (also known as trolley bus, trolley coach, trackless trolley, trackless tram – in the 1910s and 1920s – or trolley, road tram) is an electric bus that draws power from dual overhead wires (generally suspended from roadside posts) 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 (or pantograph). 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.

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 (Biela Valley, near Dresden), 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 (Mercédès-Électrique-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 (Mercédès-Électrique-Stoll) system was tried in West Ham (in 1912) and in Keighley (in 1913).

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 (trams, 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. 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 (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.

Trolleybuses are uncommon today in North America, but their use is widespread in Europe and Russia. They remain common in many countries which were part of the Soviet Union. Generally trolleybuses occupy a position in usage between street railways (trams) and motorbuses. Worldwide, around 300 cities or metropolitan areas on 5 continents are served by trolleybuses (further detail under Use and preservation, below).

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, due to its history in the former Soviet Union, the largest trolleybus system in the world in terms of route length while another formerly Soviet city, Minsk, has the largest system in terms of number of routes (which also date back to the Soviet era). Landskrona has the smallest system in terms of route length, while Mariánské Lázně is the smallest city to be served by trolleybuses. Opened in 1914, Shanghai's trolleybus system is the oldest 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.