There are a lot of trolley system in the world, not maybe as many as you would expect. However, very few in North America. The overwhelming majority of rail and

There are a lot of trolley system in the world, not maybe as many as you would expect. However, very few in North America. The overwhelming majority of rail and buses in the US are not electrified. Usually they have some limited battery for very short range operations. In many places they also have an additional diesel generator, often just for operation and emergencies, not operation.