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Busscar trolleybus in São Paulo, Brazil
Solaris trolleybus in Landskrona, Sweden
Video of a trolleybus in Ghent, Belgium

A trolleybus (also known as trolley bus, trolley coach, trackless trolley, trackless tram – in the 1910s and 1920s[1] – or trolley, road tram[2][3]) 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.[4] Altogether, more than 800 trolleybus systems have existed, but not more than about 400 concurrently.[5]

History

[edit]
The Elektromote, the world's first trolleybus,[6] in Berlin, Germany, 1882

The trolleybus dates back to 29 April 1882, when Dr. Ernst Werner Siemens demonstrated his "Elektromote" in a Berlin suburb.[7] This experiment continued until 13 June 1882, after which there were few developments in Europe, although separate experiments were conducted in the United States.[8] In 1899, another vehicle which could run either on or off rails was demonstrated in Berlin.[9] 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.[10] 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.[8] 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.

A double-deck trolleybus in Reading, England, 1966

Leeds and Bradford became the first cities to put trolleybuses into service in Great Britain, on 20 June 1911.[9] 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.[11] 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).[12][13]

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.[14] 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.[15]

MU ZiU-9 in Soviet Union, 1987

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.[16] 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).

The Shanghai trolleybus system is currently the oldest in the world.
Some coal mines also operate separate trolleybus systems 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, 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).[17] 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.

Transit authorities in some cities have reduced or discontinued the 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, new systems opened in Lecce, Italy, in 2012; in Malatya, Turkey, in 2015;[18] and in Marrakesh, Morocco, in 2017.[19] Beijing and Shanghai have been expanding their respective systems, with Beijing expanding to a 31-line system operated with a fleet of over 1,250 trolleybuses.[20] Trolleybuses have been long encouraged in North Korea with the newest city to have a network being Manpo in December 2019.[21] Since the year 2022, the city of Prague is constructing a new trolleybus system.[22] Meanwhile, in 2023, plans for a trolleybus line in Berlin were scrapped in favour of a solution with battery-powered vehicles.[23]

Vehicle design

[edit]
Diagram of a 1947-built Pullman Standard model 800 trolleybus, a type still running in Valparaíso (Chile)
  1. Parallel overhead lines (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

Modern-design vehicles

Advantages

[edit]
A San Francisco Muni trolleybus (ETI 14TrSF) climbing Nob Hill

Comparison to trams

[edit]
  • Cheaper infrastructure – The initial start up cost of trams is much higher, due to rail, signals, and other infrastructure. Trolleybuses can pull over to the kerb 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 climbing – Trolleybuses' rubber tyres have better adhesion than trams' steel wheels on steel rails, giving them better hill-climbing capability and braking.
  • Easier traffic avoidance – Unlike trams (where side tracks are often unavailable), 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.
  • Quietness – Trolleybuses are generally quieter than trams.
  • Easier training – The control of trolleybuses is relatively similar to motorbuses; the potential operator pool for all buses is much larger than for trams.

Comparison to motorbuses

[edit]
Trolleybus on tunnel line in Tateyama
Underground trolleybus at Kurobe Dam Station
  • Better hill climbing – Trolleybuses are better than motorbuses on hilly routes, as electric motors provide much higher static torque at start-up, an advantage for climbing steep hills. Unlike internal 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. Given their acceleration and braking performance, trolleybuses can outperform diesel buses on flat stretches as well, which makes them better for routes that have frequent stops.
  • Environmentally friendly – Trolleybuses are usually more environmentally friendly in the city than fossil fuel or hydrocarbon-based vehicles (petrol/gasoline, diesel, alcohol, etc.). Power from a centralized plant, even taking into account transmission losses, is often produced more efficiently, is not bound to a specific fuel source, and is more amenable to pollution control as a point source, unlike individual vehicles with exhaust gases and particulates at street level. Trolleybuses are especially favoured where electricity is abundant, cheap, and renewable, such as hydroelectric. Systems in Seattle and in Vancouver, BC, 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.
  • Trolleybuses can generate electricity from kinetic energy while braking, a process known as regenerative braking. For regenerative braking to function, there must be another bus on the same circuit needing power, an electric storage system on the vehicle or the wire system, or a method to send the excess power back to the commercial electric power system. Otherwise the braking energy must be dissipated in resistance grids on the bus; this is called "dynamic braking". The use of trolley buses also eliminates pollution during idling, thus improving air quality.
  • Minimal noise pollution – Unlike trams or gasoline and diesel buses, trolleybuses are almost silent, lacking the noise of a combustion engine or wheels on rails. Most noise comes from auxiliary systems such as power steering pumps and air conditioning. Early trolleybuses without these systems were even quieter and in the United Kingdom were sometimes referred to as the "Silent Service". This however can also be seen as a disadvantage, with some pedestrians falling victim to what was known as "Silent Death" (in Britain) or "Whispering Death" (in Australia).[citation needed]
  • Usable in enclosed space – The absence of exhaust gases allows trolleybuses to operate underground. In Cambridge, Massachusetts, trackless trolleys survived because Harvard Station, where several bus lines terminate, is in a tunnel once used by streetcars. Although diesel buses do use the tunnel, there are limitations due to exhaust fumes, which running the trolleybuses through aids in ventilation. Also, the trackless trolleys continue to have popular support. The only trolleybus systems in Japan, the Tateyama Tunnel Trolleybus and Kanden Tunnel Trolleybus lines, both run in tunnels serving the Kurobe Dam and Tateyama Kurobe Alpine Route, and were converted from normal diesel buses specifically for their lack of exhaust. Though both systems are replaced to be battery-driven as of 2025.
  • Longevity and maintenance – Electric motors typically last longer than internal combustion motors, and cause less secondary damage from vibration, so electric buses tend to be very long-lived compared to motorbuses. As the basic construction of buses has not changed much in the last 50 plus years, they can be upgraded such as when air conditioning was retrofitted to many trolleybuses. Such upgrades are often disproportionately expensive. Wheelchair lifts are relatively simple to add; kneeling front suspension is a common feature of air suspension on the front axle in lieu of springs. In comparison to battery-powered buses, the lack of a specially designed battery or fuel cell (typically with expensive patents) decreases the price and weight, and in locations with a sufficient power delivery network, the trolleybus is cheaper and easier to maintain in comparison to those requiring charging stations.[dubious – discuss]
A Rocar DAC 217E articulated trolleybus in Bucharest, Romania, in April 2007
Pole bases with springs and pneumatic pole lowering cylinders
Insulated poles, contact shoes, and pull–ropes

Disadvantages

[edit]

Comparison to trams

[edit]

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 required – Trolleybuses must be driven like motorbuses, requiring directional control by the driver.
  • Higher rolling resistance – Rubber-tired vehicles generally have more rolling resistance than steel wheels, which decreases energy efficiency.
  • Less efficient use of right-of-way – Lanes 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 loading – Implementation 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

[edit]
  • Difficult to re-route – When 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,[24] 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.
  • Aesthetics – The jumble of overhead wires may be seen as unsightly.[25] Intersections often have a "webbed ceiling" appearance, due to multiple crossing and converging sets of trolley wires.
  • Dewirements – Trolley 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.[26]
  • Unable to overtake other trolleybuses – 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, with the latter an increasingly common feature of new trolleybuses.
  • Higher capital cost of equipment – Trolleybuses 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 required – Drivers must learn how to prevent dewiring, slowing down at turns and through switches in the overhead wire system, for example.[27]
  • Overhead wires create obstruction – Trolleybus systems employ overhead wires above the roads, often shared with other vehicles. The wires can restrict tall motor vehicles such as delivery trucks ("lorries") 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.

Off-wire power developments

[edit]
On this articulated Beijing trolleybus, the operator uses ropes to guide the trolley poles to contact the overhead wires.

With the re-introduction of hybrid designs, trolleybuses are no longer tied to overhead wires. The Public Service Company of New Jersey, with Yellow Coach, developed "All Service Vehicles"; trackless trolleys capable of operating as gas-electric buses when off wire, and used them successfully between 1935 and 1948. Since the 1980s, systems such as Muni in San Francisco, TransLink in Vancouver, and 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 China, North America and 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 trackless trolleys equipped with small hybrid diesel-electric power units for operating short distances off-wire were placed in service by SEPTA in 2008. This is instead of the trolleys using a conventional diesel drive train or battery-only system for their off-wire movement.[28]

A dual-mode bus operating as a trolleybus in the Downtown Seattle Transit Tunnel, in 1990
Trolleybus with battery pack and full dual-mode capability on the streets of Brest, Belarus

King County Metro in Seattle, Washington and the MBTA in Boston's Silver Line have used dual-mode buses that run on electric power from overhead wires on a fixed right-of-way and on diesel power on city streets. Metro used special-order articulated Breda buses, introduced in 1990, and most were retired in 2005. A limited number of the Breda dual-mode buses had their diesel engines removed, and operated exclusively as trolleybuses until 2016.[29] Since 2004, the MBTA has used dual-mode buses on its Silver Line (Waterfront) route. The last of these were replaced by diesel hybrid and battery-electric buses in June 2023.[30]

In-Motion Charging

[edit]
In-Motion Charging additional batteries charging at Palmovka Prague

IMC (In-Motion Charging)[31]trolleybuses are equipped with a light-weight battery, the size of which is adapted to the line profile used. This battery allows them not to depend on overhead lines. They can thus operate with a mix of electric wire and batteries (60% of the time on the wire and 40% on the battery). With the development of battery technology in recent years, trolleybuses with extended off-wire capability through on-board batteries are becoming popular. The on-board battery is charged while the vehicle is in motion under the overhead wires and then allows off-wire travel for significant distances, often in excess of 15 km.[32][33] Such trolleybuses are called, among others, trolleybuses with In-Motion Charging, hybrid trolleybuses, battery trolleybuses and electric buses with dynamic charging. The main advantages of this technology over conventional battery electric buses are reduced cost and weight of the battery due to its smaller size, no delays for charging at end stops as the vehicle charges while in motion and reduced need for dedicated charging stations that take up public space. This new development allows the extension of trolleybus routes or the electrification of bus routes without the need to build overhead wires along the whole length of the route. Cities that utilize such trolleybuses include Beijing,[34] Ostrava,[33] Shanghai,[32] Mexico City,[35] Saint Petersburg,[36] and Bergen.[37] The new trolleybus systems in Marrakesh, Baoding[38] and Prague are based exclusively on battery trolleybuses. In 2020, the city of Berlin, Germany announced plans to build a new trolleybus system with 15 routes and 190 battery trolleybuses.[39] However, in early 2023 it was announced that the planned lines would use battery powered electric buses instead.[23][40]

Introducing new flexible, high-capacity public transport of in-motion charging (IMC) trolleybuses are electric buses that can charge dynamically via an overhead contact network and can run on batteries for up to half of their route. Because an IMC bus is operated electrically just as a tramcar without limitation of the range. It concept of trolleybus and ebus with Battery electric bus. IMC500 transfers energy from the infrastructure to the vehicle at a power of up to 500 kW. The e.g. 2 x 160 kW motors are supplied in parallel to the battery charging with e.g. 200 kW.[41][42]

Erik Lenz from Vossloh Kiepe introduced the term In-Motion Charging (IMC) as a new branding concept in 2014 during the trolley:motion conference in Hamburg [43]. The purpose of this terminology was to improve the public perception of trolleybuses by highlighting their main advantage: the ability to recharge batteries while in motion, simultaneously carrying passengers.

The word trolleybus originates from 1882, when Werner von Siemens presented an early electrically powered vehicle that collected current from overhead wires through a small, four-wheeled trolley running on them. However, for more than a century, modern trolleybuses have used current collectors without an actual trolley.

After that Erik Lenz contributed as Kiepe Electric the input of the UITP Knowledge Brief "In-Motion Charging - Innovative Trolleybus"[1] published in May 2019 followed by "Infrastructure for In-Motion Charging Trolleybus Systems" [2].

Other considerations

[edit]

With increasing diesel fuel costs and problems caused by particulate matter and NOx emissions in cities, trolleybuses can be an attractive alternative, either as the primary transit mode or as a supplement to rapid transit and commuter rail networks.

Trolleybuses are quieter than internal combustion engine vehicles. Mainly a benefit, it also provides much less warning of a trolleybus's approach. 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.

Trolleybuses can share overhead wires and other electrical infrastructure (such as substations) with tramways. This can result in cost savings when trolleybuses are added to a transport system that already has trams, though this refers only to potential savings over the cost of installing and operating trolleybuses alone.

The two parallel wires

[edit]

The wires are attached to poles next to the street and carefully stretched and mounted so that they are the same width apart and same height over the road (usually about 18 to 20 feet (~5.7m)). The pair of wires is insulated from the poles and provides about 500 to 600 volts to the bus below.[44]

Wire switches

[edit]
Trolleybus wire switch (Type Soviet Union)
A switch in parallel overhead lines[45]

Trolleybus wire switches (called "frogs" in the UK) are used where a trolleybus line branches into two or where two lines join. A switch may be either in a "straight through" or "turnout" position; it normally remains in the "straight through" position unless it has been triggered, and reverts to it after a few seconds or after the pole shoe passes through and strikes a release lever (in Boston, the resting or "default" position is the "leftmost" position). Triggering is typically accomplished by a pair of contacts, one on each wire close to and before the switch assembly, which power a pair of electromagnets, one in each frog with diverging wires ("frog" generally refers to one fitting that guides one trolley wheel/shoe onto a desired wire or across one wire. Occasionally, "frog" has been used to refer to the entire switch assembly).

Multiple branches may be handled by installing more than one switch assembly. 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 the wires over the left-turn lane, and another switch is mounted closer to or in the intersection to choose between straight through and a right turn[46] (this would be the arrangement in countries such as the United States, where traffic directionality is right-handed; in left-handed traffic countries such as the United Kingdom and New Zealand, the first switch (before the intersection) would be used to access the right-turn lanes, and the second switch (usually in the intersection) would be for the left-turn).

Three common types of switches[46] 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 considerable power from the overhead wires, usually by accelerating, at the moment the poles pass over the contacts (the contacts are lined up on the wires in this case). If the trolleybus "coasts" through the switch, the switch will not activate. Some trolleybuses, such as those in Philadelphia and Vancouver, have a manual "power-coast" toggle switch that turns the power on or off. This allows a switch to be triggered in situations that would otherwise be impossible, such as activating a switch while braking or accelerating through a switch without activating it. One variation of the toggle switch will simulate accelerating by causing a larger power draw (through a resistance grid), but will not simulate coasting and prevent activation of the switch by cutting the power.

A Selectric[47] switch has a similar design, but the contacts on the wires are skewed, often at a 45-degree angle, rather than being lined up. This skew means that a trolleybus going straight through will not trigger the switch, but a trolleybus making a turn will have its poles match the contacts in a matching skew (with one pole shoe ahead of the other), which will trigger the switch regardless of power draw (accelerating versus coasting).

For a Fahslabend switch, the trolleybus' 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).

Trailing switches (where two sets of wires merge) do not require action by the operator. The frog runners are pushed into the desired position by the trolley shoe, or the frog is shaped so the shoe is guided onto the exit wire without any moving parts.

Manufacturing

[edit]
Further information: List of trolleybus manufacturers
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.[5]: 114  In the 2000s it was effectively rendered obsolete by low-floor designs.

Well over 200 different trolleybus makers have existed – mostly commercial manufacturers, but in some cases (particularly in communist countries), built by the publicly owned operating companies or authorities.[5]: 91–125  Of the defunct or former trolleybus manufacturers, the largest producers in North America and Western Europe – 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).[5] The largest former trolleybus manufacture is Trolza (formerly Uritsky, or ZiU) since 1951, until they declared their bankruptcy in 2017, building over 65000 trolleybuses. Also, Canadian Car and Foundry built 1,114 trolleybuses based on designs by Brill.[5]

As of the 2010s, at least 30 trolleybus manufacturers exist. They include companies that have been building trolleybuses for several decades, such as Škoda since 1936 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 Russia ZiU/Trolza has historically been the world's largest trolleybus manufacturer, producing over 65,000 since 1951, mostly for Russia/CIS countries, but after its bankruptcy, its facilities were partially loaned out to PC Transport Systems. Škoda is Western and Central Europe's largest and the second largest in the world, having produced over 14,000 trolleybuses since 1936, mostly for export, and it also supplies trolleybus electrical equipment for other bus builders such as Solaris, SOR and Breda. 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.[48]: 134 

Transition to low-floor designs

[edit]

A significant change to trolleybus designs starting in the early 1990s was the introduction of low-floor models, which began only a few years after the first such models were introduced for motorbuses. These have gradually replaced high-floor designs, and by 2012, every existing trolleybus system in Western Europe had purchased low-floor trolleybuses, with the La Spezia (Italy) system being the last one to do so,[49] and several systems in other parts of the world have purchased low-floor vehicles.

In the United States, some transit agencies had already begun to accommodate persons in wheelchairs 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.[50]: 61  The Americans with Disabilities Act of 1990 required that all new transit vehicles placed into service after 1 July 1993 be accessible to such passengers.[51]

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

Trolleybuses in other countries also began to introduce better access for the disabled in the 1990s, when the first two low-floor trolleybus models were introduced in Europe, both built in 1991, a "Swisstrolley" demonstrator built by Switzerland's NAW/Hess and an N6020 demonstrator built by Neoplan.[52][53] 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.[54] The first Solaris "Trollino" made its debut in early 2001.[55]: 30  In the former Soviet Union countries, Belarus' Belkommunmash built its first low-floor trolleybus (model AKSM-333) in 1999,[56] and other manufacturers in the former Soviet countries joined the trend in the early 2000s.

However, because the lifespan of a trolleybus is typically longer than that of a motorbus, the budget allocation and purchase typically factored in the longevity; the introduction of low-floor vehicles applied pressures on operators to retire high-floor trolleybuses that were only a few years old and replace them with low-floor trolleybuses.[57] Responses varied, with some systems keeping their high-floor fleets, and others retiring them early but, in many instances, selling them second-hand for continued use in countries where there was a demand for low-cost second-hand 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,[57] a choice later also made by Lucerne.

The Vancouver trolleybus system completed the transition to an exclusively low-floor fleet in 2009.

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.[58] Wellington, New Zealand, took delivery of its first low-floor trolleybus in March 2003,[59] and by the end of 2009 had renewed its entire fleet with such vehicles.[60] Unlike Europe, where low floor means "100%" low floor from front to back, most "low floor" buses on other continents are actually only low-entry or part-low floor.

In the Americas, the first low-floor trolleybus was a Busscar vehicle supplied to the São Paulo EMTU system in 2001.[61] In North America, wheelchair lifts were again chosen[57] 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.[61] 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.[48]: 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.[51] Some transit operators have needed to modify their maintenance facilities to accommodate this change, a one-time expense.

Double-decker trolleybuses

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A trolleybus in Bradford in 1970. The Bradford Trolleybus system was the last one to operate in the United Kingdom; closing in 1972.

Since the end of 1997, no double-decker trolleybuses have been in service anywhere in the world, but, in the past, several manufacturers made such vehicles. Most builders of double-deck trolleybuses were in the United Kingdom, but there were a few, usually solitary, instances of such trolleybuses being built in other countries, including in Germany by Henschel (for Hamburg); in Italy, by Lancia (for Porto, Portugal); in Russia, by the Yaroslavl motor plant (for Moscow) and in Spain, by Maquitrans (for Barcelona).[5] British manufacturers of double-deck trolleybuses included AEC, BUT, Crossley, Guy, Leyland, Karrier, Sunbeam and others.[5]

In 2001, Citybus (Hong Kong) converted a Dennis Dragon (#701) into a double-decker trolleybus,[62] and it was tested on a 300-metre track in Wong Chuk Hang in that year.[62] 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]
Monument to Crimean Trolleybus
Main article: Trolleybus usage by country

There are currently 300 cities or metropolitan areas where trolleybuses are operated,[4] and more than 500 additional trolleybus systems have existed in the past.[5] 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.[4] However, there are eight systems existing in North America and nine in South America.[4]

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.[5] 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[63] – but operation of trolleybuses does not necessarily occur on a regular schedule of dates at these museums.

System of eBRT

[edit]

Trolleybuses are also used in bus rapid transit systems (electrified bus rapid transit, eBRT), the current routes are listed below:

Country City System name Opened Lines Number of stations Length Notes
 China Beijing Beijing Bus Rapid Transit Line 1 [zh] 2 January 2016 1 17 15.51 km (9.64 mi) Beijing BRT
Beijing Bus Rapid Transit Line 3 [zh] 15 January 2015 1 22 22.95 km (14.26 mi)
Shanghai Yan'an Road Medium Capacity Bus Transit System 1 February 2017 1 25 17.5 km (10.9 mi) Trolleybuses in Shanghai
Zhengzhou Zhengzhou BRT Route B2 1 January 2021 2 17 12.5 km (7.8 mi)
 Brazil São Paulo São Mateus–Jabaquara Metropolitan Corridor 3 December 1988 8 8 33 km (21 mi) Trolleybuses in São Paulo
 Ecuador Quito MetrobusQ, El Trole 17 December 1995 1 39 24 km (15 mi) Trolleybuses in Quito
 France Lyon Lyon trolleybus line C1 [fr] 12 October 2006 2 7 8.4 km (5.2 mi) Trolleybuses in Lyon
Lyon trolleybus line C2 [fr] 29 August 2011 4 10 12.1 km (7.5 mi)
Lyon trolleybus line C3 [fr] 30 October 2007 3 17 12 km (7.5 mi)
Nancy 5 April 2025 1 25 10 km (6.2 mi) Trolleybuses in Nancy
 Italy Rimini and Riccione Metromare 23 November 2019 1 17 9.8 km (6.1 mi) Trolleybuses in Rimini
Pescara La Verde 11 September 2025 1 26 8.15 km (5.06 mi) Trolleybuses in Pescara
 Mexico Mexico City Trolleybuses in Mexico City 9 March 1951 11 303 203.64 km (126.54 mi)
 Morocco Marrakesh BRT Marrakesh 29 September 2017 1 8 8 km (5.0 mi)
 Spain Castellón de la Plana Castellon TRAM [es] 25 June 2008 1 19 7.765 km (4.825 mi) Trolleybuses in Castellón de la Plana
 Turkey Malatya Trambus [tr] 10 March 2015 1 53 37 km (23 mi)
Şanlıurfa Trambus (Sanliurfa) [tr] 28 April 2023 1 63 7.7 km (4.8 mi)

See also

[edit]

Notes

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Further reading

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Trolleybus

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from Grokipedia
A trolleybus, also known as a trolley coach or trackless trolley, is a rubber-tired that draws its power from a pair of overhead electrical wires using two trolley poles mounted on its roof, enabling zero-emission operation in urban environments without the need for onboard fuel storage. The technology originated in the late , with early experiments dating to in , , and the first practical in-service use emerging between the and in , where it served as a flexible alternative to rail-based streetcars. Trolleybuses gained widespread adoption in the early to mid-20th century, particularly in and , peaking with hundreds of systems worldwide by the 1940s due to their quiet operation, rapid acceleration, and superior performance on hilly terrain compared to diesel buses. However, many networks were dismantled from the to as cities prioritized the route flexibility and lower infrastructure costs of conventional motor buses, leading to a sharp decline in global usage. In recent decades, trolleybuses have experienced a resurgence driven by environmental regulations and the push for , with modern systems incorporating batteries for limited off-wire operation to enhance flexibility. As of 2025, approximately 257 cities across more than 40 countries operate trolleybus networks, comprising over 22,000 vehicles and serving as a key component of low-carbon public transit in urban corridors. Notable advantages include near-zero tailpipe emissions when powered by renewable sources, reduced , lower maintenance needs, and longer vehicle lifespans, making them particularly suitable for dense, topographically challenging cities like and Zurich. Despite high initial costs for overhead wiring, ongoing innovations in in-motion charging and hybrid designs position trolleybuses as a viable option for decarbonizing bus fleets amid global electrification trends.

Overview

Definition and Principles

A trolleybus is an that operates on rubber tires and draws its power from a pair of overhead wires suspended above the roadway, using articulated poles or bows to maintain . Unlike rail-based electric vehicles such as trams or , trolleybuses do not require fixed tracks and can maneuver flexibly on standard streets, making them suitable for urban routes with mixed traffic. This design allows for zero-emission operation in electrified sections while providing the versatility of a conventional bus. The core principles of trolleybus operation involve collecting (DC) from the overhead lines to power onboard electric that drive the wheels. Current collection occurs via two parallel overhead conductors—one carrying the positive supply and the other serving as the return—spaced approximately 0.6 meters apart, contacted by spring-loaded or pneumatically operated trolley poles fitted with carbon or metal shoes for continuous electrical connection during vehicle movement. The power supply is typically DC at nominal voltages of 600 or 750 , delivered through a system that ensures stable energy transfer without onboard generation. is achieved by converting this into mechanical via series-wound DC motors or, in modern configurations, AC induction motors powered through inverters, enabling smooth acceleration and for efficiency. Key components include the overhead contact system, comprising a messenger wire supporting the trolley wire (for positive current) and an auxiliary return wire, which together form a complete circuit isolated from the ground due to the vehicle's rubber tires. Power conversion occurs at trackside substations, where (AC) from the utility grid is rectified to DC and stepped down to the required voltage, with substations spaced 1 to 5 kilometers apart to minimize voltage drops. Vehicle grounding is facilitated entirely through the return wire, preventing stray currents and ensuring safe operation on non-conductive road surfaces.

Global Context and Usage

As of 2025, trolleybus systems operate in 257 cities across more than 40 countries worldwide, comprising a global fleet of 22,137 vehicles that serve millions of passengers daily as a sustainable urban mobility option. These systems are most prevalent in and , where they account for the majority of operational networks and vehicles, driven by a focus on zero-emission . In , which hosts over half of the world's trolleybus systems, concentrations are highest in , with and operating the most systems (dozens each as of 2021), alongside notable networks in (14 systems), Czechia (13), and (10). Revivals and modernizations have occurred in cities like , where the system integrates advanced battery-assisted technology for enhanced flexibility, and earlier efforts in supported network upgrades before recent plans for partial retirement. In , expansions continue in major cities such as , which maintains one of the largest fleets with over 1,250 dual-mode vehicles across 31 routes, and , where recent infrastructure improvements have extended service to key urban areas. overall operates 13 systems, contributing significantly to the region's vehicle count through ongoing electrification initiatives. The Americas represent a smaller share, with only a handful of surviving systems in , including , , , and , which persist as holdouts amid a broader decline that accelerated after the due to shifting priorities toward automobiles and diesel buses. In Latin America, trolleybuses form part of emerging electric fleets, though battery-electric buses are increasingly dominant. Trolleybuses play a key role in sustainable urban transport, offering zero tailpipe emissions and supporting decarbonization goals, with notable growth in (eBRT) applications from 2020 to 2025. In , e-bus fleets, including trolleybuses, expanded at an average annual rate of 33.5% since , reaching over 6,000 electric buses by 2024. Economically, trolleybus systems involve high initial infrastructure costs for overhead wiring and substations, but they can yield long-term savings through lower expenses compared to diesel buses, with vehicle lifespans often extended. Worldwide, these networks span thousands of kilometers of routes, enabling efficient service in densely populated areas.

History

Early Invention and Adoption

The invention of the trolleybus is credited to Ernst Werner von Siemens, who demonstrated the world's first electric trackless trolley, called the Electromote, on April 29, 1882, in the suburb of Gross-Lichterfelde. This experimental vehicle featured a 2.5-horsepower powered by overhead wires through a bow-shaped collector, marking a significant step toward electric road transport independent of rails. The transition to commercial operation occurred nearly two decades later, with the launch of the first regular passenger-carrying trolleybus service on July 10, 1901, between Königstein and Bad Königstein in , . Developed by in collaboration with engineer Max Schiemann, this 3.5-kilometer line used under-running trolley poles for power collection and operated until 1904, proving the feasibility of the system for short urban and suburban routes. A similar early system ran from 1901 to 1913 between and in , utilizing self-propelled vehicles by Lombard-Gerin, further validating the technology's practicality. During the 1910s and 1920s, trolleybus adoption accelerated in , particularly in , , and the , where cities sought efficient electric alternatives to trams and horse-drawn vehicles for flexible routing. In the UK, the first permanent service commenced in on June 20, 1911, while expanded with multiple lines, including extensions of Schiemann's designs. In the United States, the inaugural commercial trolleybus line debuted in on September 2, 1910, connecting Hollywood to the Laurel Canyon development using converted buses with overhead power collection. This early American implementation highlighted the trolleybus's advantages over contemporary battery-electric vehicles, including virtually unlimited range via continuous overhead supply and high starting torque from electric motors, which proved ideal for hilly urban areas. Key technological advancements drove this initial spread, including refinements to series-wound DC electric motors for better hill-climbing capability and the development of more reliable overhead contact systems, such as spring-loaded trolley poles, which reduced wire wear and improved current collection on city streets. These innovations enabled trolleybuses to serve irregular routes without the infrastructure costs of rail tracks, fostering growth in urban centers across continents by the mid-1920s.

Expansion, Peak, and Decline

Following , trolleybus systems underwent significant expansion globally, driven by the need for efficient urban transport in rebuilding cities. In the , where the first system had opened in in 1933, postwar development exploded, with numerous cities and towns introducing or extending passenger and cargo trolleybus networks to support industrialization and . By the late 1940s, this boom contributed to a worldwide peak, with the number of trolleybus systems reaching 366 in 1949. The 1950s marked the zenith of trolleybus adoption, particularly in regions like and the , where low operating costs—due to electric requiring no onboard —and zero tailpipe emissions made them attractive for dense urban routes. In the United States, over 60 cities operated trolleybus services by 1940, expanding further postwar to handle increased ridership, representing about 10 percent of national transit activity at the decade's peak. also saw notable growth, exemplified by , , which introduced its first 20 trolleybuses in 1947 to replace damaged tram infrastructure after the 1948 riots, rapidly expanding to serve the city's growing population. The decline began in the and accelerated through the , primarily due to the rise of diesel buses, which offered cheaper without extensive overhead wiring and benefited from advancing for larger, more flexible vehicles. In the , many systems converted, such as Boston's, which phased out trolleybuses by the early 1960s amid falling ridership and economic pressures on transit operators. Globally, the number of systems halved by the 1980s, as automotive shifts prioritized road expansion and private vehicle use over fixed electric rail alternatives. Regional differences shaped the trajectory, with trolleybuses persisting longer in communist bloc countries like those in the , where emphasis on from imported oil sustained operations despite broader declines elsewhere. The oil crises further highlighted these advantages, prompting minor revivals and reduced shutdown rates in by underscoring the reliability of electric systems amid fuel shortages.

Infrastructure

Overhead Contact System

The overhead contact system (OCS) for trolleybuses consists of twin parallel wires designed to deliver power while accommodating urban street layouts. The primary trolley wire, typically made of grooved hard-drawn or alloys such as with a cross-section of around 80 mm², serves as the main conductor for power transfer and is positioned at a standard height of approximately 5.2 meters above the street surface to ensure clearance for vehicles and pedestrians. A supporting messenger wire, often stranded galvanized , runs parallel to provide tension and stability, connected via droppers and hangers spaced at regular intervals. These components are mounted on poles spaced 30 to 50 meters apart, with span lengths not exceeding 36.6 meters to minimize sag and maintain consistent contact. Power distribution in the OCS relies on traction substations spaced every 1 to 3 kilometers, which convert high-voltage from the utility grid to 600-750 V suitable for trolleybus operation. Voltage drops along the lines, which can reach significant levels due to the dual-conductor setup and urban loads, are managed through auxiliary feeder cables that connect substations directly to key points in the network, ensuring stable supply even during . Design standards for the OCS emphasize adaptability to urban constraints, including the use of flexible booms and hangers to guide wires through curves with radii as tight as 30 meters, preventing misalignment and arcing. Materials such as alloys and galvanized provide inherent weatherproofing against and accumulation, with insulators often made of or composite to withstand environmental exposure. At intersections, specialized crossings maintain wire continuity without interrupting power flow. Maintenance practices for the OCS involve regular inspections to detect , , and tension issues, with walking patrols conducted biannually to examine poles, wires, and insulators, and annual aerial assessments to measure contact wire exceeding 30% for replacement. These protocols help mitigate downtime from weather-related damage like buildup. Initial installation costs average around $1.5 million per kilometer, including wiring and electrical supply, while annual upkeep typically ranges from $10,000 to $50,000 per kilometer depending on system age and traffic volume.

Switches and Terminals

In trolleybus networks, wire switches, also known as frogs in some regions, are essential mechanisms that guide the trolley poles at junctions where lines branch or merge, enabling route changes without physical intervention on the vehicle. Common types include power-on/power-off switches, where the driver toggles vehicle power to direct the pole along the desired wire; Selectric switches, which use solenoids activated by current draw from the pole to shift the contact; and Fahslabend switches, which are radio-controlled for precise operation via driver signals. These switches are typically designed in narrow angles of 10° or 20° to accommodate smooth pole transitions, with options for left- or right-hand configurations to suit network layouts. Crossover switches facilitate lane changes by allowing poles to transfer between parallel overhead wires, often incorporating spring-loaded guides to maintain contact during maneuvers. Terminal operations at the end of lines rely on specialized configurations to reverse direction efficiently, avoiding the need for manual pole flipping. Loop or turning loop setups route the overhead wires in a circular path, permitting the trolleybus to complete a while keeping poles attached and maintaining polarity. In constrained urban spaces, such as narrow valleys, turntables rotate the entire vehicle 180° to realign poles with the return wire. Shunt wires provide short auxiliary sections of overhead contact for brief off-wire movements during terminal maneuvers, such as repositioning or access. Modern advancements since the have introduced remote-controlled switches in systems like Vancouver's TransLink network, where drivers activate switches via onboard radio transmitters to minimize errors and speed up operations. Safety interlocks, integrated into switch mechanisms, detect pole position and vehicle approach to prevent misalignment, reducing the risk of pole damage or de-wiring incidents. These features enhance reliability in high-traffic environments. Challenges in switch and terminal design include managing electrical arcing, which occurs as poles pass through switches and can accelerate wear on contacts; techniques, such as insulated guides and low-resistance materials, mitigate this by minimizing spark duration. Historically, manual hand-throw switches required operator intervention, leading to longer dwell times, whereas current (PLC)-based allows seamless, driver-initiated switching, significantly streamlining operations compared to earlier methods.

Vehicle Design

Chassis, Body, and Propulsion

Trolleybus chassis are typically produced by specialized manufacturers such as , , and Hess, often adapted from standard bus or frames to integrate electric components while maintaining robust structural integrity for urban operations. These modifications often include reinforced mounting points for motors and batteries, with articulated versions featuring a flexible to accommodate higher passenger capacities of up to 150 individuals in lengths around 18 meters. Such designs enhance maneuverability in congested city environments compared to rigid configurations. The body construction of trolleybuses employs lightweight materials like aluminum or panels to balance durability and weight reduction, facilitating and compliance with modern safety standards. Vehicles commonly feature 2 to 4 doors per side for rapid passenger flow, with configurations varying by model—such as three doors on standard units and four on articulated ones—to support high-volume routes. is prioritized through integrated features like low-floor designs and deployable ramps, enabling users and those with mobility aids to board without assistance. Propulsion in modern trolleybuses relies on AC electric motors, typically asynchronous or permanent magnet synchronous types rated at 200 to 300 kW, powered via inverters from the DC overhead supply, delivering high starting torque for smooth acceleration and effective handling of steep urban grades up to 15%, outperforming diesel buses in hilly terrain. Historical vehicles used series or compound-wound DC motors. Regenerative braking systems further enhance efficiency by converting kinetic energy during deceleration into electrical power, recovering approximately 20-30% of braking energy to reduce overall consumption. This process integrates seamlessly with the overhead power supply, minimizing wear on mechanical brakes. Trolleybuses utilize rubber tires for superior road flexibility and traction on varied surfaces, contrasting with the rigidity of rail-bound systems like trams. systems are standard to absorb shocks from urban potholes and uneven pavement, ensuring comfort and during frequent stops and starts.

Power Collection and Electrical Components

Trolleybuses employ a dual-pole for power collection, consisting of two parallel poles mounted on the that contact separate overhead wires to complete the electrical circuit, one for positive and one for return current. Each pole is typically equipped with a grooved carbon shoe or wheel at the top end to maintain sliding contact with the wire, reducing wear and ensuring reliable current transfer up to 1800 A in high-demand scenarios. Pole lengths generally range from 4 to 6 meters, allowing sufficient reach for urban overhead s while accommodating height variations. To enhance operational safety, modern trolley poles feature auto-retraction mechanisms that lower the poles automatically upon detection of wire loss or dewirement, preventing damage to the overhead infrastructure and allowing quick recovery without manual intervention. For systems requiring greater stability at higher speeds, bow-type collectors may be used instead of straight poles; these curved designs distribute more evenly, minimizing vibrations and dewirement risks during or on uneven routes. variants, while rare in trolleybuses due to the preference for simpler pole systems, occasionally appear in specialized designs for improved high-speed performance. Onboard electrical components include resistors for traditional speed control, which dissipate excess energy as heat to regulate motor acceleration, though these have largely been supplanted since the 1980s by more efficient solid-state power electronics, including thyristor choppers for DC motors and IGBT-based inverters for AC motors, enabling precise pulse-width modulation of power delivery to the traction motors. Auxiliary systems, such as lighting, doors, and control electronics, are powered by onboard batteries, typically standard lead-acid units providing short-term backup during minor disruptions. Control systems integrate solid-state accelerators and inverters to manage and speed, with feeding energy back to the overhead lines via the power . Contact pressure from spring-loaded shoes on the poles is maintained at 50-100 N to ensure consistent wire engagement without excessive wear. Fault protection is provided by circuit breakers that interrupt power flow during or short-circuit events, safeguarding onboard and preventing arcing. Overall system efficiency for energy conversion in trolleybuses reaches 80-90%, benefiting from direct overhead power draw that minimizes losses associated with onboard storage. Spring-loaded shoes further aid arc minimization by maintaining firm, continuous contact, reducing electrical arcing during movement and extending component life.

Operational Aspects

Route Planning and Maintenance

Route design for trolleybus systems is inherently constrained by the fixed overhead wiring infrastructure, which restricts operational flexibility and requires routes to be aligned precisely with the wire network to ensure continuous power supply. Unlike diesel or battery-electric buses, trolleybuses cannot deviate significantly from pre-planned paths without losing propulsion, necessitating thorough urban planning to accommodate street geometries, intersections, and obstacles while minimizing visual and spatial impacts. Integration with traffic signals is a key consideration, often involving transit signal priority systems to enhance flow and reduce dwell times at intersections. Urban operating speeds for trolleybuses vary, averaging 12-18 km/h in revenue service depending on the system (e.g., around 12 km/h in Seattle), with maximum speeds typically reaching 40-50 km/h on suitable alignments; peak-hour headways commonly set at 5-10 minutes to balance capacity and efficiency. Scheduling trolleybus services emphasizes high reliability, particularly in sections covered by overhead wires, where on-time performance can exceed 75% system-wide, benefiting from the absence of refueling stops and consistent electric . Overall bus on-time metrics for operators like , which includes trolley routes, are around 76-78% as of 2025 for regular services, though wired segments often achieve better adherence due to predictable power delivery. Contingencies for wire faults, such as pole dewirements or line disruptions, include immediate driver protocols like activating emergency flashers, engaging brakes, and isolating power, followed by deployment of tow trucks for repositioning or temporary swaps to diesel-hybrid backups in hybrid-equipped fleets to maintain service continuity; modern hybrid designs allow limited off-wire operation using batteries during disruptions, improving reliability as of 2025. Maintenance routines for trolleybuses focus on both and components to ensure and longevity, with daily inspections of trolley poles, shoes, and wiring connections performed by operators to detect wear, arcing, or misalignment that could lead to dewirements. Quarterly overhauls typically cover propulsion motors, pantographs, and electrical systems, conducted in specialized depots equipped with wire simulators to replicate overhead contact conditions without live power. Trolleybus vehicles generally have a lifecycle of 15 years under standards, reflecting their robust electric design, while energy use ranges from approximately 1.3-1.8 kWh/km, with operating costs varying by location and era (historically around $0.20-0.30 per km in the early when including maintenance and upkeep). Safety protocols are paramount in trolleybus operations, mandating minimum overhead clearance of at least 5.4 meters (17.6 feet) for wires above roadways to prevent collisions with vehicles or structures, as enforced by utilities like Muni. Emergency off-wire procedures require drivers to immediately secure the vehicle, notify dispatch, and use auxiliary batteries—if equipped—for limited movement to a safe reconnection point, with ground crews trained to handle live wire risks under strict lockout-tagout standards. These measures, combined with regular infrastructure patrols, help mitigate hazards from high-voltage systems operating at 600 volts DC.

Driver and Passenger Experience

Trolleybus drivers utilize accelerator pedals or, in some advanced models, controllers for , similar to those in conventional electric buses, allowing precise control over the vehicle's electric motors. These controls are integrated into the driver's cabin alongside standard wheels and braking systems, with additional monitors displaying the alignment and status of the trolley poles to maintain continuous contact with the overhead wires. When poles dewire during operation, drivers must manually reposition them using onboard tools or by maneuvering the vehicle, a requiring specialized that typically lasts 4-6 weeks to ensure safe and efficient recovery procedures. Passengers experience a notably quiet ride in trolleybuses, with interior noise levels typically ranging from 50 to 60 decibels during operation, compared to over 70 decibels in diesel buses, due to the absence of internal engines. (HVAC) systems are electrically powered, drawing from the overhead lines to provide consistent climate control without the vibrations associated with engine-driven units. Standard trolleybuses accommodate 80 to 120 passengers, including 40 to 60 seated and the remainder standing, depending on the vehicle's length and configuration. Accessibility features in trolleybuses have advanced significantly since the with the introduction of low-floor designs, reducing entry heights to approximately 300 millimeters to facilitate level boarding at standard curbs. Many models incorporate kneeling suspension systems that hydraulically lower the front end by several inches upon stopping, further easing access for passengers with mobility aids. Modern fleets often include signage on doors, handrails, and priority seating areas to assist visually impaired riders, aligning with broader transit accessibility standards. User feedback highlights the smoother acceleration provided by electric propulsion, which minimizes jerky starts and stops, potentially reducing instances of compared to diesel vehicles with their abrupt gear shifts. Historically, passengers noted a characteristic "trolleybus swing," a gentle swaying motion caused by the arcing and of the trolley poles as the vehicle navigates curves or obstacles, adding a distinctive rhythmic quality to the ride. These elements contribute to an overall comfortable experience, enhanced by the vehicle's body design that prioritizes spacious interiors and ergonomic seating.

Advantages and Disadvantages

Environmental and Efficiency Benefits

Trolleybuses generate zero tailpipe emissions, eliminating direct releases of harmful pollutants like particulate matter, nitrogen oxides, and that are characteristic of diesel-powered buses. This feature significantly improves local air quality in urban areas where trolleybus systems operate. When the supply draws from renewable sources, lifecycle CO2 emissions can be reduced by 29-87% compared to conventional diesel buses. Additionally, trolleybuses contribute to of 10-15 dB(A) at typical urban speeds relative to diesel buses, fostering quieter street environments and mitigating impacts on residents. In terms of energy efficiency, trolleybuses consume about 1.5-2 kWh per kilometer, substantially lower than the 4-6 kWh equivalent for diesel buses when accounting for energy content. systems in trolleybuses recover during deceleration, yielding savings of 15-25% in overall energy use by feeding power back into the overhead lines. The overhead contact infrastructure supporting trolleybuses has a typical lifespan of 40-50 years, enabling long-term operational reliability and reduced replacement frequency compared to vehicle-centric systems. Trolleybuses align with broader objectives, such as those outlined in the European Union's Green Deal, which targets zero-emission new city buses by 2030 to curb transport-related greenhouse gases. By avoiding exhaust heat emissions, they help minimize contributions to effects, supporting cooler cityscapes without the thermal output of internal combustion engines. In Zurich's extensive trolleybus network, the shift to electric operation on key lines has already prevented over 540 tons of CO2 emissions annually through diesel displacement. Analyses indicate that trolleybus systems achieve 10-20% lower long-term operating costs than diesel equivalents, driven by energy efficiency and reduced maintenance needs. Modern battery-assisted designs allow limited off-wire operation, partially addressing flexibility concerns in operations.

Infrastructure and Flexibility Limitations

Trolleybus systems require substantial initial investment in overhead wiring and supporting infrastructure, with construction costs typically ranging from $1 to $5 million per kilometer depending on urban density and site conditions. This is significantly higher than the approximately $0.5-1 million per kilometer for implementing bus lanes, which involve simpler road marking and minimal structural changes. Retrofitting existing cities poses additional challenges, including excavation for pole foundations, coordination with utility lines, and disruption to ongoing traffic. The fixed nature of the overhead contact system limits operational flexibility, as trolleybuses cannot deviate from wired routes during or emergencies without , potentially halting service on affected segments. Route expansions or modifications are constrained by regulations, where even minor adjustments—such as a 20% realignment to accommodate new developments—necessitate extensive rewiring and approvals, delaying implementation by months or years. Trolleybus infrastructure is vulnerable to weather-related disruptions, particularly in cold climates where ice accumulation on wires can cause arcing, power loss, or require specialized de-icing operations to maintain service. interference from poles and wires also elevates accident risks due to maneuvering constraints around fixed supports. Additional drawbacks include the visual clutter created by poles and wires, which can detract from urban aesthetics and require careful design to minimize community opposition. Overhead components typically last 40-50 years before needing replacement, with renewal costs averaging $0.9-1.5 million per kilometer for wires and associated hardware.

Comparisons

Versus Trams

Trolleybuses and trams share a reliance on overhead catenary wires for electric power collection, but differ fundamentally in ground infrastructure: trolleybuses operate on rubber tires using standard roadways, eliminating the need for dedicated rail tracks required by trams. This avoids substantial track installation and maintenance expenses, yielding potential savings of several million dollars per kilometer depending on local conditions. In terms of operational flexibility, trolleybuses behave like conventional buses, enabling easy lane changes, , and adaptation to mixed urban traffic without the constraints of fixed rails that limit trams to predefined routes. This makes trolleybuses particularly advantageous in congested or evolving street environments where rerouting or temporary deviations are common. Trams generally offer higher passenger capacity, with vehicles accommodating 180 to 260 passengers compared to 155 for typical electric trolleybuses, and they can sustain urban speeds up to 50 km/h more reliably on dedicated alignments. However, trolleybuses produce less street-level noise, avoiding the wheel-rail contact that generates higher noise levels for trams compared to rubber-tired electric vehicles. Trolleybuses suit retrofitting in cities lacking rail infrastructure, leveraging existing roads for quicker, lower-disruption , while trams excel on segregated rights-of-way where their low enables lower energy use per passenger-kilometer than rubber-tired systems like trolleybuses.

Versus Motor Buses

Trolleybuses demonstrate significantly higher energy efficiency compared to diesel motor buses, typically achieving 2-3 times better performance in terms of use per kilometer due to the direct electric propulsion system that eliminates losses associated with internal combustion engines. For instance, trolleybuses emit approximately 0.5-1 kg of CO2 equivalent per kilometer when powered by average grid electricity, in contrast to 1-2 kg CO2 per kilometer for diesel buses, depending on quality and load factors. This efficiency translates to substantial reductions; studies in urban settings like show that replacing diesel buses with trolleybuses can decrease emissions by 0.29-0.39 kg CO2 per kilometer. Additionally, trolleybuses require no onboard storage or refueling logistics, avoiding the operational disruptions and concerns inherent in diesel bus fleets. Maintenance requirements for trolleybuses favor lower vehicle wear compared to motor buses, as electric motors endure far longer with minimal intervention, often lasting over 1 million kilometers before major overhaul, while diesel engines typically reach 500,000-800,000 kilometers. This stems from fewer and the absence of combustion-related degradation, resulting in reduced costs for , transmissions, and engine rebuilds—electric bus systems, including , incur about 40% less expense per mile than diesel equivalents. However, these savings are partially offset by the need for ongoing upkeep of the overhead wiring and substations, which can add specialized costs not present in motor bus operations. Overall, lifecycle analyses indicate trolleybuses yield 15-20% lower total expenditures when wire infrastructure is amortized over high-utilization routes. In terms of , trolleybuses are constrained to fixed routes equipped with overhead lines, limiting their adaptability across a full , whereas motor buses offer complete flexibility for rerouting or expansion without changes. Converting a bus corridor to trolleybus operation typically costs $10-20 million for a 5-10 km segment, primarily due to wiring installation at $1-1.5 million per kilometer, though this investment enables long-term operational savings in dense urban areas. Diesel and hybrid motor buses, by contrast, allow rapid deployment and network-wide coverage at lower upfront costs, making them preferable for low-density or evolving transit systems. Performance-wise, trolleybuses excel in hill-climbing and , capable of handling grades up to 25% and achieving quicker starts from stops thanks to instant from electric motors, outperforming traditional diesel buses on challenging . By 2025, hybrid motor buses have narrowed this gap with improved electric assist for better low-speed and reduced emissions, yet trolleybuses maintain a 15% edge in long-term operating costs due to sustained efficiency on electrified routes. This makes trolleybuses particularly advantageous in hilly cities, where motor buses may require more frequent maintenance under stress.

Technological Developments

Off-Wire and Hybrid Systems

Off-wire technologies enable trolleybuses to operate without continuous contact with overhead wires for limited distances, typically using onboard energy storage systems such as batteries or supercapacitors to bridge gaps of 1 to 10 kilometers. These systems store energy collected from the wires during normal operation, allowing the vehicle to navigate temporary deviations, construction zones, or areas where wiring installation is impractical. For instance, battery-assisted trolleybuses in European systems can achieve off-wire ranges of approximately 10 km with capacities around 45 kWh, supporting speeds suitable for urban routes while maintaining zero-emission performance. Hybrid trolleybus models, which combine overhead wire power with onboard batteries, have gained prominence since the , offering dual-mode operation for greater route flexibility. In , cities like and St. Gallen have deployed such systems, where battery-powered trolleybuses operate off-wire for significant portions of their routes, utilizing only about 28% of the traditional contact line infrastructure. These vehicles recharge batteries via the wires during connected segments, enabling autonomous travel for up to 10 km at typical urban speeds, which enhances operational efficiency in mixed wired and unwired environments. In-motion charging represents a key advancement in hybrid systems, where trolleybuses draw power from overhead wire segments during operation and supplement with depot-based charging for full-day service. This approach integrates short electrified overhead sections—often covering 20-30% of routes—with battery support, minimizing the need for extensive wiring while ensuring continuous energy supply. The International Union of Public Transport (UITP) highlights that in-motion charging trolleybuses can operate on rechargeable batteries off-wire, combining the reliability of wired power with battery autonomy for urban networks. Relevant standards, such as for conductive charging systems, support these hybrid setups, with updates in 2023 and beyond accommodating high-power levels up to 300 kW via for efficient depot or opportunity charging. This facilitates rapid energy transfer during stops or at terminals, aligning with the power demands of heavy-duty electric buses in trolleybus applications. systems in the 151-300 kW range are increasingly adopted for both in-motion and static charging, ensuring compatibility with evolving infrastructure. The adoption of off-wire and hybrid systems yields notable benefits, including reduced overhead wiring requirements and lower infrastructure costs compared to fully wired networks. In Beijing, over 1,250 battery-assisted trolleybuses operate across 31 routes, demonstrating large-scale implementation of hybrid technology for emission-free urban transit. Similarly, Vancouver's TransLink has ordered up to 512 new trolleybuses, with deliveries expected to begin in 2026, each with a 20 km off-wire range, which supports route adaptability and cuts maintenance expenses associated with extensive wiring. These developments underscore the role of hybrid trolleybuses in scaling zero-emission public transport while addressing traditional infrastructure limitations.

Low-Floor and Specialized Variants

The development of low-floor trolleybuses began in the , driven by the need to improve passenger and boarding efficiency through the adoption of systems that eliminated traditional designs. These vehicles reduced floor heights to approximately 350-400 mm above the ground, compared to the 900 mm typical of earlier models, allowing level boarding from standard curbs without steps. The first low-floor trolleybus entered service in , , in 1993, marking a significant shift in design that prioritized ergonomic benefits for passengers with mobility challenges. By the 2010s, low-floor configurations had become predominant in new trolleybus fleets worldwide, reflecting broader trends in public transit toward accessible vehicles that facilitate faster dwell times and higher ridership. This evolution addressed longstanding barriers in high-floor systems, where passengers often navigated multiple steps, but it introduced engineering challenges, particularly in weight distribution. In low-floor trolleybuses equipped with onboard batteries for hybrid operations, the placement of heavy battery packs—often offset to maintain structural integrity—can disrupt balance, leading to issues like uneven axle loading and reduced stability during turns or on inclines. Double-decker trolleybuses emerged in as a capacity-enhancing variant, particularly in the , where they were integrated into London's extensive conversion from trams to trolleybuses starting in 1931. These two-story vehicles offered seating for over 100 passengers, doubling the throughput on busy urban routes compared to single-deck models. However, their height—typically exceeding 4 meters—necessitated overhead wire clearances of at least 4.5-5.6 meters to avoid contact during operation, limiting deployment in areas with low infrastructure or bridges. Outside the UK and select cities, double-decker trolleybuses remain rare today, comprising a small fraction of the global fleet due to these spatial constraints and a shift toward single-deck designs for versatility. Specialized variants have further expanded trolleybus applications, including articulated bi-body models for (BRT) systems, which connect two chassis sections via a flexible joint to accommodate 150-200 passengers on high-demand corridors. In , , the trolleybus network employs a fleet of over 100 articulated vehicles on its 18-km central line, integrating electric overhead power with dedicated lanes to enhance urban mobility efficiency. Accessibility features, such as deployable ramps, became standard on new U.S. trolleybuses following the Americans with Disabilities Act of 1990, which mandated wheelchair-compatible lifts or ramps on all fixed-route transit vehicles acquired after July 1993 to ensure equitable access.

Manufacturing and Deployment

Key Manufacturers

In the early , the was home to several prominent trolleybus manufacturers, with the emerging as a key player. Founded in 1868 in , Brill produced a range of urban transit vehicles, including trolleybuses, from the through the 1950s, supplying models like the Brill TC44 that served major cities such as and . The company ceased trolleybus production amid declining demand for overhead wire systems in the postwar era, shifting focus to buses before its acquisition and eventual closure in 1954. Similarly, the , established in 1887, became another major U.S. producer of trolleybuses during the same period, competing directly with Brill in building electric coaches for and city routes. Known for innovative designs, St. Louis delivered over 1,000 trolleybus units in the 1930s and 1940s, including articulated models for high-capacity lines in cities like and , before exiting the market in the 1950s due to the rise of diesel buses. In the , Trolza (formerly the Uritsky Plant or ZiU) established post-1940s dominance in trolleybus manufacturing, becoming the primary supplier for the expansive Soviet network. Located in , the factory began of models like the ZiU-5 in 1947 and later the in 1971, equipping over 90 cities across the USSR and exporting to ; it produced tens of thousands of units until financial challenges led to in 2022. As of 2025, the global trolleybus market is led by European and Asian firms, with of holding approximately 30% of the market through its production of low-emission models like the Trollino series. Chinese manufacturer BYD has gained prominence with battery-hybrid trolleybuses, integrating overhead wire capability in vehicles such as the K9 variant for flexible urban deployment. Swiss company Hess AG specializes in low-floor trolleybuses, exemplified by the lighTram 25, which features advanced accessibility and systems for alpine and urban routes. Czech firm produces articulated trolleybuses like the ForCity Smart, designed for high-capacity BRT corridors with modular electric propulsion. Key component suppliers include Vossloh Kiepe, which provides control systems, traction converters, and complete packages for trolleybuses, drawing on decades of experience in e-bus technology. Schunk supplies pantographs and current collectors essential for reliable overhead contact, supporting both classic and off-wire operations in modern fleets. The overall trolleybus components market is valued at around $2.3 billion annually as of 2023, driven by demands. Recent trends indicate a shift toward Asian production, with Chinese firms accounting for about 60% of global output since 2020, fueled by exports from companies like and Zhongtong amid Europe's push for sustainable transit. Custom builds for rapid transit (eBRT) systems highlight growing adaptation of trolleybus tech to hybrid overhead-battery formats for enhanced route flexibility.

Current Systems and Preservation Efforts

As of 2025, trolleybus networks operate in 257 cities across more than 40 countries, comprising a global fleet of 22,137 vehicles that provide sustainable urban mobility to millions of passengers daily. dominates this landscape, hosting the majority of systems with operational networks in over 200 cities, including major expansions in , , and , where new in-motion charging trolleybus lines integrated with corridors serve growing urban populations. In , Switzerland's maintains one of the continent's most extensive networks, featuring six lines spanning 54 kilometers of route length and emphasizing electrification for environmental goals. The preserves limited but significant operations, notably in , where the Municipal Transportation Agency deploys approximately 300 electric trolley coaches across eight routes and is undergoing fleet modernization with battery-assisted models. Revival efforts since the 2010s have reinvigorated trolleybus adoption, driven by commitments to net-zero emissions and urban sustainability. In Mexico City, the system was revived in 2019 with the introduction of modern Yutong trolleybuses on electrified bus rapid transit corridors, marking a shift from diesel operations and enhancing zero-emission public transport in a high-density metropolis. Italy's Bologna exemplifies hybrid advancements, where a network of five urban routes operational since 1991 has incorporated dual-mode vehicles capable of off-wire running, supporting ongoing expansions amid Europe's push for greener fleets. Post-2020, global trolleybus deployments have accelerated due to net-zero targets, with new systems and modernizations in cities like Jinan emphasizing integration with existing infrastructure to reduce greenhouse gases and operational costs. Preservation initiatives worldwide focus on maintaining historical trolleybuses through dedicated museums and heritage operations, safeguarding cultural and technical legacies amid the shift to modern variants. The Trolleybus Museum at Sandtoft in the houses the world's largest collection of preserved trolleybuses, with over 50 vehicles from various eras, including restorations that involve thousands of volunteer hours and costs exceeding £25,000 per unit for mechanical and electrical overhauls. In , Vancouver's active trolleybus system includes heritage elements, such as preserved 1940s-era vehicles occasionally operated for special events. The in , preserves several historic U.S. trolleybuses, including examples from and other cities, with full restorations for operational heritage vehicles typically ranging from $250,000 to $500,000 depending on scope and materials. These efforts, often funded by nonprofits and grants, highlight the educational value of trolleybuses. Looking ahead, approximately 50 new trolleybus systems are planned or under development by 2030, primarily in and , fueled by advancements in in-motion charging and hybrid technologies that address flexibility concerns. 's trolleybus fleet is projected to grow by 120% from 2022 levels by 2030, supported by EU-funded projects promoting zero-emission corridors in cities across , , , and . In , China's ongoing integrations with BRT networks signal continued expansion, though challenges from rapid , such as infrastructure conflicts and land-use pressures, may temper rollout speeds in densely populated areas.

References

  1. https://www.sfmta.com/getting-around/muni/munis-electric-trolley-buses
  2. https://www.siemens.com/global/en/company/about/history/technology/transportation-technology/road-transportation.html
  3. https://onlinepubs.trb.org/Onlinepubs/sr/sr200/sr200-001.pdf
  4. https://pdfs.semanticscholar.org/66f4/2507117f9beaf0b3cdc333b63f9bebad7c10.pdf
  5. https://www.uitp.org/publications/global-trolleybus-figures-2025/
  6. https://onlinepubs.trb.org/Onlinepubs/sr/sr200/200.pdf
  7. https://www.uitp.org/wp-content/uploads/sites/7/2025/09/20250923_Policy-Brief_In-Motion-Charging-Trolleybus_WEB.pdf
  8. https://www.trb.org/publications/tcrp/tcrp_webdoc_6-e.pdf
  9. https://unece.org/DAM/trans/doc/2014/wp29/ECE-TRANS-WP29-2014-70e.pdf
  10. https://www.trolleybus.org.uk/WhatisaTB.htm
  11. https://scbist.com/scb/uploaded/331_frey_s_railway_electrification_systems_engineering.pdf
  12. https://worldpopulationreview.com/country-rankings/trolleybus-usage-by-country
  13. https://cleantechnica.com/2025/05/14/why-modern-cities-are-embracing-trolleybuses-again/
  14. https://trolleybuses.org/history/
  15. https://theicct.org/wp-content/uploads/2025/05/ID-316-%25E2%2580%2593-LatAm-bus-monitor_spotlight_final.pdf
  16. https://www.sciencedirect.com/science/article/pii/S095965262033852X
  17. https://www.wired.com/2010/04/0429first-trolleybus/
  18. http://www.trolleybus.co.uk/history1.htm
  19. https://www.britishtrolley.org.uk/the-trolleybus/
  20. https://mehva.org/60years
  21. http://www.tbus.org.uk/article.htm
  22. http://www.tramz.com/co/bg/b/be.html
  23. https://www.engineeringenotes.com/electrical-engineering/electric-traction-electrical-engineering/overhead-construction-for-trams-trolley-buses-and-railways-electricity/37170
  24. https://www.macimpulse.net/blog/components-of-an-overhead-contact-system-powering-sustainable-urban-mobility
  25. https://onlinepubs.trb.org/onlinepubs/tcrp/tcrp_rpt_07-b.pdf
  26. https://www.mdpi.com/1996-1073/15/5/1629
  27. https://research.tudelft.nl/files/134950144/A_Complete_DC_Trolleybus_Grid_Model_With_Bilateral_Connections_Feeder_Cables_and_Bus_Auxiliaries.pdf
  28. https://www.tbus.org.uk/overhead.htm
  29. https://onlinepubs.trb.org/Onlinepubs/sr/sr200/200-018.pdf
  30. https://www.apta.com/wp-content/uploads/Standards_Documents/APTA-RT-FS-S-006-02-Rev-2.pdf
  31. https://www.urban-transport-magazine.com/en/bus-electrification-a-comparison-of-capital-costs/
  32. https://www.tbus.org.uk/overhead.pdf
  33. https://www.sustainable-bus.com/trolleybus-tramway/trolleybus-market-zero-emissions/
  34. https://www.urban-transport-magazine.com/en/bi-articulated-trolleybuses-for-prague-and-bratislava/
  35. https://www.skodagroup.com/reference/skoda-hcity-12
  36. https://www.bozankaya.com.tr/assets/uploads/kataloglar/troleybus-EN8.pdf
  37. https://www.urban-transport-magazine.com/en/a-new-trolleybus-in-the-market/
  38. https://www.sciencedirect.com/science/article/abs/pii/S0378779614000716
  39. https://onlinepubs.trb.org/Onlinepubs/sr/sr200/200-013.pdf
  40. https://www.wabteccorp.com/transit-bus/electric-power-collection/trolley-poles
  41. https://kingcountymetro.blog/2016/10/27/keeping-our-trolleys-safe-and-reliable/
  42. http://university.listenlights.com/2017/09/08/types-of-traction-collectors/
  43. https://civitas.eu/sites/default/files/possibilities_of_trolleybus_transportation_energy_demand_reduction.pdf
  44. https://villamosok.hu/troli/ik-280-gvm/e_index.html
  45. http://www.tbus.org.uk/engineering.htm
  46. https://onlinepubs.trb.org/Onlinepubs/sr/sr200/sr200-017.pdf
  47. https://www.mdpi.com/2227-7390/13/12/2022
  48. https://seattletransitblog.com/2009/09/22/the-trolley-argument/
  49. https://traffic2.fpz.hr/index.php/PROMTT/article/download/1484/359
  50. https://app.powerbigov.us/view?r=eyJrIjoiZDMwMWExOTMtOTY3ZC00MTU5LTgxMDgtODM4MTZiYTExMzJkIiwidCI6ImJhZTUwNTlhLTc2ZjAtNDlkNy05OTk2LTcyZGZlOTVkNjljNyJ9
  51. https://seattletransitblog.com/wp-content/uploads/2025/11/A.-King-County-Metro-Transit-2025-System-Evaluation.pdf
  52. https://www.seattletimes.com/seattle-news/transportation/your-metro-bus-is-on-time-more-often-than-you-may-realize-heres-why/
  53. https://www.kiro7.com/news/investigates/problems-with-new-electric-buses-cause-delayed-commutes-safety-problems_/461067141/
  54. https://www.jeeng.net/pdf-65456-5927?filename=ESTIMATION%2520OF%2520THE%2520RUNNING.pdf
  55. http://metro.kingcounty.gov/up/projects/pdf/TrolleyBus_PreliminaryFindings_April2011.pdf
  56. https://www.sciencedirect.com/science/article/pii/S0306261924019688
  57. https://www.sfmta.com/sites/default/files/reports-and-documents/2017/10/section_7_transit_operations.pdf
  58. https://techpub.prevostcar.com/content/media/14603/view
  59. https://www.mobilityinnovations.com/wp-content/uploads/sites/5/2021/09/MI_BROCHURE_2021_FINAL_27_08_21_V3_EMAIL.pdf
  60. https://www.aikos.smm.lt/en/studyprogramm/_layouts/15/asw.aikos.registersearch/objectformresult.aspx?o=prog&f=progen&key=1005&pt=of&ctx_sr=5ap4z%252Bwievri04xeoygushetiaaikos.smm.lt
  61. https://www.apta.com/wp-content/uploads/Standards_Documents/APTA-BTS-BO-RP-001-07.pdf
  62. https://blog.cleverdevices.com/electric-vehicles-noise-pedestrian-safety
  63. https://www.guchen.com/all-electric-bus-ac/bus-hvac.html
  64. https://onlinepubs.trb.org/onlinepubs/tcrp/tcrp_webdoc_6-b.pdf
  65. https://www.curbsideclassic.com/bus-stop-classic/bus-stop-classics-new-flyer-d40lf-north-americas-first-low-floor-bus/
  66. https://freedmanseating.com/2016/10/06/interurban-trolley-welcomes-new-trolley-buses-press-release/
  67. https://www.metro-magazine.com/10158058/translink-begins-installation-of-braille-signage-at-every-bus-stop
  68. https://www.team-bhp.com/forum/electric-cars/296121-motion-sickness-electric-cars-2.html
  69. https://www.1900s.org.uk/1900s-trolley-buses.htm
  70. https://www.transportation.gov/sites/dot.gov/files/2023-12/OSTX-Momentum-Toolkit-ZEB_Edition2_Final.pdf
  71. https://blog.ucs.org/jimmy-odea/electric-vs-diesel-vs-natural-gas-which-bus-is-best-for-the-climate/
  72. https://www.sciencedirect.com/science/article/pii/S2352146518306227
  73. https://teem.ornl.gov/documents/publications/EV_BUS_energy_acceptedversion.pdf
  74. https://www.mdpi.com/2079-9276/7/3/43
  75. https://www.eeas.europa.eu/eeas/european-green-deal-commission-proposes-2030-zero-emissions-target-new-city-buses-and-90-emissions_en
  76. https://new.abb.com/news/detail/91812/abb-technologies-help-buses-in-zurich-become-more-energy-efficient
  77. https://asric.africa/sites/default/files/2025-05/ES_V4_Issu%25201_7.pdf
  78. https://www.nrdc.org/bio/zak-accuardi/new-toolkit-supports-bus-priority-implementation
  79. https://trolleybuses.org/disadvantages/
  80. https://willbrownsberger.com/saying-good-bye-to-the-trolleys/
  81. https://buzzer.translink.ca/2023/01/this-is-how-we-de-ice-the-overhead-wires-that-power-our-trolley-electric-buses/
  82. https://onlinepubs.trb.org/Onlinepubs/trr/1995/1503/1503-009.pdf
  83. https://ti.org/antiplanner/?p=20095
  84. https://solar.lowtechmagazine.com/2009/07/get-wired-again-trolleybuses-and-trolleytrucks/
  85. https://www.witpress.com/Secure/elibrary/papers/UT00/UT00002FU.pdf
  86. https://www.researchgate.net/publication/302481143_Tram_and_trolleybus_net_traction_energy_consumption_comparison
  87. https://www.emobility-engineering.com/electric-trams/
  88. https://www.sciencedirect.com/science/article/pii/S0016236125016631
  89. https://changing-transport.org/wp-content/uploads/2023_Comparative-analysis-of-bus-technologies_v2.pdf
  90. https://www.researchgate.net/publication/265819854_Comparative_Analysis_of_Bus_and_Trolleybus_Related_GHGs_Emissions_and_Costs_in_Lithuania
  91. https://www.driveelectrictn.org/maintenance-costs-for-evs-vs-ice-vehicles/
  92. https://www.uti.edu/blog/diesel/how-long-diesel-engines-last
  93. https://www.quora.com/What-is-the-life-expectancy-of-electric-motors-in-vehicles
  94. https://city-hikes.com/2025/07/01/back-to-the-future-on-a-trolleybus/
  95. https://medium.com/the-future-is-electric/the-return-of-the-electric-bus-you-forgot-about-c2c740078e07
  96. https://en.yutong.com/technology/industry-insights/technologies/2024/1836653671878889472.shtml
  97. https://www.mdpi.com/2071-1050/16/24/11303
  98. https://www.venturasystems.com/10-hess-trolleybuses-began-service-in-fribourg-for-tpf/
  99. https://www.urban-transport-magazine.com/en/new-battery-trolleybuses-for-the-expansion-plan-in-st-gallen/
  100. https://www.sgs.com/en/news/2025/10/worlds-first-iec-61851-23-2023-cb-certificate-issued-for-electric-vehicle-dc-charging-stations
  101. https://dataintelo.com/report/high-power-pantograph-charging-for-buses-market
  102. https://www.urban-transport-magazine.com/en/electric-bus-operation-on-beijings-roads-battery-trolley-buses/
  103. https://www.urban-transport-magazine.com/en/solaris-wins-the-first-large-contract-on-north-american-market-a-new-trolleybus-fleet-in-vancouver/
  104. http://www.tbus.org.uk/Kerr_Vossloh.pdf
  105. https://brtguide.itdp.org/branch/master/guide/vehicles/vehicle-floor-height
  106. https://www.apta.com/wp-content/uploads/Resources/resources/reportsandpublications/Documents/Trends-in-Public-Transportation-Vehicle-Fleets.pdf
  107. https://metro.kingcounty.gov/up/projects/pdf/Metro_TB_20110527_Final_LowRes.pdf
  108. https://www.ltmuseum.co.uk/collections/stories/transport/londons-electric-trams-and-trolleybuses
  109. https://pva.org/wp-content/uploads/2021/09/ada_access_transit.pdf
  110. https://www.midcontinent.org/rollingstock/builders/brill.htm
  111. https://www.american-rails.com/slcc.html
  112. https://rusbankrot.ru/en/bankruptcy-and-liquidation/the-oldest-trolleybus-plant-of-engels-went-bankrupt-/
  113. https://www.gminsights.com/industry-analysis/trolley-bus-market
  114. https://www.sustainable-bus.com/news/first-half-2025-electric-bus-market-europe/
  115. https://www.marketsandmarkets.com/blog/AT/electric-bus-market
  116. https://kiepe-group.com/en/products/bus
  117. https://www.schunk-group.com/transit-systems/en
  118. https://dataintelo.com/report/global-trolley-bus-market
  119. https://www.sustainable-bus.com/electric-bus/electric-bus-public-transport/
  120. https://itdp.org/2025/06/13/jinans-electric-trolleybuses-spark-a-transformation-for-china-stmagazine-36/
  121. https://www.bouygues-construction.com/blog/en/zurich-mobilite-durable/
  122. https://www.urban-transport-magazine.com/en/the-revival-of-the-emission-free-trolleybuses-in-mexico-city/
  123. https://www.urban-transport-magazine.com/en/the-bologna-process-more-electric-public-transport-to-come/
  124. https://sandtoft.org/wp/
  125. https://trolleymuseum.org/
  126. https://www.uitp.org/news/6-mobility-trends-vital-to-the-success-of-public-transport-across-central-europe/
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