Yard Limits

Yard Limits
The main track area between Yard Limit signs as designated in the Timetable. Movements of trains must be made at Restricted Speed within Yard Limits.
Yardmaster ...

Yard Limits
A portion of main track designated by yard limit signs and special instructions.
Yard Speed ...

In yard limits, it is very possible that a main line switch may be lined against the route in which you are authorized to use.

Generic description of APB .
Yard Limits (YL)
YL denotes a main track on which movements are to be at Restricted Speed. Trains can therefore occupy main tracks without further authority.

Yard A set of tracks with defined limits for LRV cleaning, repair, storage or other purposes as designated by the rules and procedures. Yard Limits A specific location that designates the separation of yard and mainline tracks.

Movements within yard limits may be made without timetable or train order authorization. Yard rules allow engineers to proceed when they see the track is clear, but not over 25mph, and not outside the yard limits.

See also: Track, Train, Yard, Switch, Operation