Editing Railroad switch (section)

== History ==
[[File:PyinOoLwin23.JPG|thumb|Control stand of a defunct railroad switch on the way from [[Pyin Oo Lwin]] to [[Goteik viaduct]] ([[Myanmar]])]]

Simple single-bladed switches were used on early wooden railways to move wagons between tracks. As iron-railed [[plateway]]s became more common in the eighteenth century, cast iron components were made to build switches with check rails.<ref>{{cite book |last=Dow |first=Andrew |date=30 October 2014 |title=The Railway: British Track Since 1804 |publisher=Pen & Sword Transport |location=Barnsley |isbn=9781473822573 |page= }}</ref>{{Page needed|date=April 2025}} In 1797, [[John Curr]] described the system that he developed which used a single iron blade, hinged on a vertical pin that was tapered to lie against the plateway.<ref>{{cite book |last=Curr |first=John |title=The Coal Viewer and Engine Builder's Practical Companion |location=Sheffield |publisher=John Northall |date=1797 |page= }}</ref>{{Page needed|date=April 2025}} By 1808, Curr's basic design was in common use.<ref>{{cite book |last=Lee |first=Charles E. |date=1937 |title=The Evolution of Railways |location=London |publisher=The Railway Gazette |page= }}</ref>{{Page needed|date=April 2025}}

The use of a sprung rail, giving a smooth transition, was patented by [[Charles Fox (engineer, born 1810)|Charles Fox]] in 1838.<ref>{{cite patent |country=GB |number=7773 |inventor=Charles Fox |title=Arrangement of Rails, for Causing a Train to Pass from One Line to Another |pubdate=1838-08-15 }}</ref>

Prior to the widespread availability of [[electricity]], switches at heavily traveled junctions were operated from a [[signal box]] constructed near the tracks through an elaborate system of rods and [[lever]]s. The levers were also used to control [[railway signal]]s to control the movement of trains over the points. Eventually, mechanical systems known as [[interlocking]]s 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. Purely mechanical interlockings were eventually developed into integrated systems with electric control. On some low-traffic branch lines, in self-contained [[marshalling yard]]s, or on [[heritage railway]]s, switches may still have the earlier type of interlocking.