Trains, trams, metros

 

Electricity is used as a source of power for traction, but also to operate points and signals and manage the traffic.

Electricity rapidly came to dominate for traction as it is inexpensive, non-polluting and permits high speeds. It is also used to control points and signalling as the systems are safer than mechanical control using cables.

The return of trams to cities and the expansoin of metro systems are due to technological advances and the desire to reduce pollution from combustion engines..