History
On early lines, vehicles were moved between tracks by means of sliding rails. The switch as we know it was patented by Charles Fox in 1832.
Prior to the widespread availability of electricity, switches at heavily travelled junctions were operated from a signal box constructed near the tracks through an elaborate system of rods and levers. The levers were also used to control railway signals to control the movement of trains over the points. Eventually, mechanical systems known as interlockings were introduced to make sure that a signal could only be set to allow a train to proceed over points when it was safe to do so. On some low-traffic branch lines, in self-contained marshalling yards, or on heritage railways, switches may still be operated in this way.
Read more about this topic: Railroad Switch
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