A trolleybus is a non-rail vehicle (usually passenger) with an electric drive that receives electric current from an external power source through the contact network by means of a rod current collector.
The trolleybus can also be equipped with battery, supercapacitor or internal combustion engine systems. One variation of the latter – when the electric and diesel engines have independent transmission – is called a duobus.
The trolleybus is used mostly in cities, but there are also intercity trolleybuses. Initially regarded as a suburban transport, later it often began to replace streetcars in areas where they are inconvenient to use, for example, in historic city centers with narrow streets.
The trolleybus occupies a special place among other modes of urban passenger transport. It is proven to be the most environmentally friendly mode of transport after the subway.
A trolleybus is a low-noise mode of public transport. Theoretically, a trolleybus can be made completely silent. Usually the noise in a trolleybus comes from the compressor, heating and air conditioning systems. However, complete quietness can also be a disadvantage, since a pedestrian may not see the approaching trolleybus and get run over.
Advantages of a trolleybus compared with a streetcar:
- the initial cost of building a trolleybus line is much lower than a streetcar line, since a trolleybus line does not require the opening of the roadway or the construction of a separate track, because the existing road infrastructure is used. It is only necessary to extend the overhead contact line network.
- Relatively high maneuverability of the trolleybus, which, however, is limited by the overhead contact network.
- trolleybus rubber tires have better traction than steel trolleybus wheels, which allows trolleybus operation on high-slope tracks.
- the pavement used by the trolleybus line can be used by motor vehicles. Motor vehicle traffic on the streetcar tracks can be difficult.
- streetcar tracks require time-consuming repair and maintenance, which the trolleybus contact network lacks.
Advantages of the trolleybus compared with the bus:
The trolleybus has an important advantage over the bus – due to electric motors having higher efficiency, they accelerate faster and can accelerate when driving uphill. That, along with the environmental friendliness of trolleybuses, made it especially advantageous in rugged terrain, where buses are difficult to overcome mountains and streetcars are not applicable due to slopes.
Modern trolleybuses are not inferior to buses in terms of comfort, and even surpass them, due to absence of gasoline smell and exhaust in the cabin.
Among other advantages of trolleybus: they do not pollute the air with combustion products; the service life of trolleybus rolling stock is longer than that of buses; maintenance costs of trolleybus fleet are less than those of buses.
Disadvantages:
- Initial deployment costs are higher for a trolleybus network than for a bus network.
- trolleybus consumes more electricity than streetcar.
- trolleybus capacity is on average lower than that of streetcars.
- trolleybus is very sensitive to pavement and overhead wires, especially to icy overhead wires.
- It is difficult to overtake one trolleybus by another, if it is not provided by the contact network.
- a trolleybus cannot change its route, although it is more flexible in this respect than a streetcar.
- the trolleybus is more dangerous than the streetcar because of “leakage currents”.
- The trolleybus is less environmentally friendly than the streetcar – when the wheels rub against the asphalt, harmful rubber dust is generated.
- there is a danger of stopping on a de-energized section at an intersection and a trolleybus arrow, for example, when being “cut off” by other traffic.
- there is an opinion that the trolleybus contact network somewhat spoils the appearance of streets, especially in historic city centers.
There are trolleybuses, albeit in small numbers, in many countries: Austria, Bulgaria, the Czech Republic, France, Germany, Hungary, Italy, the Netherlands, Spain, Sweden, Switzerland and many others.
Currently, there are more than 400 cities around the world that use trolleybuses as ground transportation. In the UK, at one point, trolleybuses were abandoned. As for the largest trolleybus fleet in Europe, it serves Athens. The total length of the contact network is more than 350 km.