SP 1976 updated 1980 (capitalization and bold per original)

93. Within yard limits, ENGINES after complying with provisions of Rules 81 or 81-A, may use main track without train-order authority, clearing the time approaching first class trains are due to leave the last preceding station where time is shown. Flag protection against trains and engines is not required.

All trains and engines must move at RESTRICTED SPEED on main track within yard limits, except where movements are governed by block signal indication. (Effective July 18, 1977)


GCOR 1st Edition (1985)

93. Yard Limit Rule: Within yard limits, the main track may be used by trains and engines, not protecting against other trains or engines. Engines must give way to trains as soon as practicable upon their approach.

Inferior trains and engines must clear the main track at the time a first class train is due to leave the nearest station in the direction of approach where time is shown.

Trains must clear other trains which are superior as prescribed by Rules 86 and S-87.

In ABS territory, information issued by the train dispatcher, either verbally or by message, may be used to determine when delayed first class trains are due to leave nearest station where time is shown.

Movements within yard limits must be made at restricted speed, unless the main track is known to be clear by a Clear, Approach Limited, Advance Approach or Diverging Clear signal.

Movements against the current of traffic must not be made unless authorized and protected by train order, track warrant, yardmaster or other authorized employee.


GCOR 2nd Edition (1989) (first rule book not to include Timetable and Train Order)

93. Yard Limit Rule: Within yard limits, the main track may be used by trains and engines, not protecting against other trains or engines. Engines must give way to trains as soon as practicable upon their approach.

Movements within yard limits must be made at restricted speed, unless the main track is known to be clear by a block signal displaying green in its aspect or part of its aspect.

Movements against the current of traffic must not be made unless authorized and protected by track warrant, track bulletin, yardmaster or other authorized employee.

Where yard limits are in effect in CTC territory, trains and engines must not enter the main track at a hand operated or spring switch without authority from the control operator.

Yard limits are in effect continuously unless otherwise specified by timetable or track bulletin.


GCOR Third edition (1994) (rule numbering change)

6.13 Yard Limits
Within yard limits, trains or engines are authorized to use the main track not protecting against other trains or engines. Engines must give way as soon as possible to trains as they approach.

All movements entering or moving within yard limits must be made at restricted speed unless operating under a block signal indication that is more favorable than Approach.

Upon observing or having advance knowledge that a block signal may require restricted speed due to yard limits, if entering or within yard limits, the movement must be at restricted speed at that block signal, or as soon as possible thereafter, consistent with good train handling.

Yard limits remain in effect continuously unless otherwise specified by special instructions or track bulletin.

Against the Current of Traffic

Movements against the current of traffic must not be made unless authorized or protected by track warrant, track bulletin, yardmaster, or other authorized employee.

In CTC Territory

Where yard limits are in effect in CTC territory, the control operator must authorize any movement on the main track. Reverse movements within the same block may be made as outlined in Rule 6.4.1 (Permission for Reverse Movements).

GCOR Fourth edition (2000)

Same as Third edition except added:

In Track Permit Territory

Where yard limits are in effect in Rule 9.15 (Track Permit) territory, all movements must receive permission from the control operator to enter the main track or to cross over from one main track to another as follows:
• A controlled signal displays a proceed indication.
• A track permit is issued.
or
• Verbal permission is granted if no track permit is in effect. Rule 9.17 (Entering Main Track at Hand-Operated or Spring Switch) applies.

(My note - Rule 9.17 is requirement to open switch and wait five minutes to provide signal protection that used to only apply in ABS)

GCOR Fifth edition (2005)

First paragraph changed to read:

Within yard limits, trains or engines are authorized to use the main track not protecting against other trains or engines, only after obtaining a track warrant, listing all track bulletins that affect their movement. Engines must give way as soon as possible to trains as they approach. Engines must keep posted as to the arrival of passenger trains and must not delay them.

GCOR Sixth edition (2010)

No apparent changes from Fifth edition


Code of Federal Regulations (enforced by the FRA)

49 CFR § 218.35 Yard limits.
(a) After August 1, 1977, yard limits must be designated by—
(1) Yard limit signs, and
(2) Timetable, train orders, or special instructions.
(b) After August 1, 1977, each railroad must have in effect an operating rule which complies with the requirements set forth below:
(1) The main tracks within yard limits may be used, clearing the time an
approaching designated class train is due to leave the nearest station where time is shown. In case of failure to clear the time of designated class trains, protection must be provided as § 218.37. In yard limits where main tracks are governed by block signal
system rules, protection as prescribed by § 218.37 is not required.
(2) Trains and engines, except designated class trains, within yard limits must move prepared to stop within one half the range of vision but not exceeding 20 m.p.h. unless the main track is known to be clear by block signal indications.
(3) Within yard limits, movements against the current of traffic on the main tracks must not be made unless authorized and protected by train order, yardmaster, or other designated
official and only under the operating restrictions prescribed in § 218.35(b)(2).
(c) Each railroad shall designate in the operating rule prescribed under paragraph (b) of this section the class or classes of trains which shall have superiority on the main track within yard limits. [42 FR 5065, Jan. 27, 1977]