Section 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 onehalf 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