The essential feature of electric traction is the removal of power generation from the train to a stationary power unit, and this fact is responsible for most of its economies and advantages. This same fact also gives rise to the great drawback of electrification, since a large amount of capital has to be expended in providing the overhead or third-rail equipment, together with the necessary feeders, transmission cables, and sub-stations. This capital once expended is definitely tied to the route and cannot be moved if the scheme does not prove a financial success.