Automatic Operation
Many crossing loops are designed to operate automatically in an unattended mode. Such loops may be track circuited with home signals cleared by the approaching train. Some loops have the points in and out of the loop operated manually, albeit more recent examples have so-called self restoring switches that allow trains to exit a loop without needing to change the points.
Other forms of remote operation included Centralized traffic control, where a train controller changes points and signals from a remote office; and driver operated points, which enable train crews to use a radio system to set the points from a distance.
Read more about this topic: Passing Loop
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