Editing Railroad switch (section)

=== Slip switches ===

==== Double slip ====
[[File:Double slip at Munich central.jpg|thumb|upright|A double switch, or double slip—the points are set to connect the upper left and lower right tracks.]]

A ''double slip switch'' (''double slip'') is a narrow-angled diagonal flat crossing of two lines combined with four pairs of points in such a way as to allow vehicles to change from one straight track to the other, alternatively to going straight across. A train approaching the arrangement may leave by either of the two tracks on the opposite side of the crossing. To reach the third possible exit, the train must change tracks on the slip and then reverse.

The arrangement gives the possibility of setting four routes, but because only one route can be traversed at a time, the four blades at each end of the crossing are often connected to move in unison, so the crossing can be worked by just two levers or point motors. This gives the same functionality of two points placed end to end. These compact (albeit complex) switches usually are found only in locations where space is limited, such as station throats (i.e. approaches) where a few main lines spread out to reach any of numerous platform tracks.

In North American English, the arrangement may also be called a ''double switch'', or more colloquially, a ''puzzle switch''. The [[Great Western Railway]] in the United Kingdom used the term ''double compound points'', and the switch is also known as a ''double compound'' in [[Victoria (Australia)]]<!-- And the rest of Australia?? -->. In Italian, the term for a double switch is {{lang|it|deviatoio inglese}}, which means ''English switch''. Likewise, it is called {{lang|nl|Engels(e) Wissel}} in Dutch and, occasionally, {{lang|de|Engländer}} ("english one", literally "Englishman") in German.

==== Single slip ====
A ''single slip switch'' works on the same principle as a double slip, but provides for only one switching possibility. Trains approaching on one of the two crossing tracks can either continue over the crossing, or switch tracks to the other line. However, trains from the other track can only continue over the crossing, and cannot switch tracks. This is normally used to allow access to sidings and improve safety by avoiding having switch blades facing the usual direction of traffic. To reach the sidings from what would be a facing direction, trains must continue over the crossing, then reverse along the curved route (usually onto the other line of a double track) and can then move forward over the crossing into the siding.

==== Outside slip ====
[[File:2001-07-19.0004.DKW-Baeseler.jpg|thumb|left|upright|A double, outside slip in Heidelberg main station]]

An ''outside slip switch'' is similar to the double or single slip switches described above, except that the switch blades are outside of the diamond instead of inside. An advantage over an inside slip switch is that trains can pass the slips with higher speeds. A disadvantage over an inside slip switch is that they are longer and need more space.

An outside slip switch can be so long that its slips do not overlap at all, as in the example pictured. In such a case a single, outside slip switch is the same as two regular switches and a regular crossing.  Double outside slip switches are only used in rare, specific cases.

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