AUTOMATIC BLOCK SYSTEM RULES NOTE: Rules 505 to 516 inclusive, will only be effective on portions of the Railroad specified in the Time Table or by General Order. 505. Block signals, cab signals, or both, govern the use of the blocks, but unless otherwise provided do not supersede the superiority of trains; nor dispense with the use or the observance of other signals whenever and wherever they may be Required. 508, Unless otherwise provided, block signals for a track apply only to trains or engines moving with the current of traffic on that track. D-508. Except where Rule 261 is in effect, trains operated against the current of traffic must observe Manual Block Rules (Rules 300 through 306). 509. When a train or engine is stopped by an automatic block signal, it may proceed: (a) On single track, when authorized by train dispatcher, and will then proceed at restricted speed or, when communication is lost or not provided, preceded by a flagman until he can see the block signal in advance in the approach or proceed indication, when flagman may be taken up and the train or engine proceed to that signal at restricted speed, or, in cab signal territory, until an approach or less restrictive indication is displayed by the cab signal. (b) On two or more tracks at restricted speed. (c) When operating under Rule 261, at restricted speed. 511. After obtaining permission as prescribed by Rule D-152, and complying with Rule 99, a crossover movement must be made as follows: (a) At crossover not equipped with center-of-crossover locking device, open the switch in the track from which the crossover movement is to start. After waiting three minutes, switch at opposite end of crossover must be opened before starting crossover movement. The crossover movement must be completed before either switch is restored to normal position. (b) At crossover equipped with center-of-crossover locking device, operate center-of-crossover lock lever to the reverse position and secure in that position with padlock. After waiting three minutes, open both switches and secure both switch stand levers with hooks. After crossover movement has been completed, restore both switches to normal position, secure switch stand levers with hooks, and operate center-of-crossover lock lever to normal position and lock with padlock. 513. After obtaining permission as prescribed by Rule D-152, and complying with Rule 99, a movement which will enter or foul the main track must not be made, except where otherwise provided, until independently operated derail in the track from which the movement is to be made is placed in non-derailing position; after waiting three minutes, the main track switch will then be opened in advance of the movement. In the absence of independently operated derail, main track switch will be opened for three minutes in advance of the movement. 514. A train or engine having accepted a proceed indication and being delayed in the block, must proceed at restricted speed to the next signal. 515. A train or engine entering a block between signals must be protected as required by the rules and must proceed at restricted speed to the next signal. 516. A train or engine having passed beyond the limits of a block must not back into that block except under authority of train order.