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A railroad switch , turnout, or [set of] points is a mechanical installation enabling railway trains to be guided from one track to another, such as at a railway junction or where a spur or siding branches off.
Double trap points are a full turnout, leading to two tongues. Usually the tongue nearer the main line is longer than the other. Trap points with a crossing are double trap points where the tongues of rail are longer, so that the trap point rail nearest the main line continues over the siding rail with a common crossing or frog.
Turnouts facing and trailing. Note that this diagram is for left-hand traffic; for right-hand traffic, "F" and "T" would be swapped. Facing or trailing are railway turnouts (or 'points' in the UK) in respect to whether they are divergent or convergent. When a train traverses a turnout in a facing direction, it may diverge onto either of the two ...
A railway track (CwthE and UIC terminology) or railroad track (NAmE), also known as permanent way (CwthE) [1] or "P Way" (BrE [2] and Indian English), is the structure on a railway or railroad consisting of the rails, fasteners, sleepers (railroad ties in American English) and ballast (or slab track), plus the underlying subgrade.
A rail break between the insulated rail joint and the track circuit feed wiring would not be detected. Failure modes that result in an incorrect "track clear" signal (known usually in North America as a "false clear") may allow a train to enter an occupied block, creating the risk of a collision. Wheel scale and short trains may also be a problem.
Double junction, or level junction (left hand running). A double junction is a railway junction where a double-track railway splits into two double track lines. Usually, one line is the main line and carries traffic through the junction at normal speed, while the other track is a branch line that carries traffic through the junction at reduced speed.
The point machine (in this case an electric motor) and associated mechanism used to operate this switch can be seen to the right in the picture. A point machine (also known as a point motor, switch machine or switch motor) is a device for operating railway turnouts especially at a distance.
In dual gauge lines, turnouts (railroad switches) are more complex than in single-gauge track, and trains must be safely signalled on both of the gauges. Track circuits and mechanical interlocking must also operate on both gauges.