The Trolleybus

... differs from the tram firstly in that it doesn't need a track to run on, and secondly in that (because there is no track to complete the circuit) it needs two wires and two poles – each pole connecting with one wire.

The trolleybus was also sometimes known, in its early days, as the trackless tram.

The world's first passenger tram was the Swansea and Mumbles Railway. The Mumbles Railway Act was passed by Parliament in 1804, and this first horse–drawn passenger tramway started operating in 1807. It was worked by steam from 1877, and from 1929 by very large (106–seater) electric tramcars, until closure in 1961.

The advantages of trolleybuses over trams include cheaper infrastructure (no need to build tracks), better hill climbing, and less disturbance to other road traffic. On the downside: they require more driver control, are less energy–efficient (because rubber tyres have more friction), and need wider lanes because they may move from side to side.

© Haydn Thompson 2019