Contents

Rule 251: giving trains authority to move on signal indication in one direction
Rule 261: giving trains authority to move on signal indication in both directions
Rule 261: reverse movement beyond the limits of the block
Rule 504: for trains doing work within Traffic Control System

 
Rule 17: for dimming lights on locomotives
Rule 17 is actually a collection of rules that govern which lights are to be on on a locomotive at given times and to when they should be dimmed. These rules may vary from railroad to railroad but generally follow a similar pattern. The general purpose of the rule is to make sure that the locomotive is visible, without creating undue glare for others in the area.
• Except when an engine is clear of the main and stopped, both the front (and rear if so equipped) headlights should be on.
• The light in the direction of travel should be a full brightness except:
o 1. At stations and yards where switching is being done.
o 2. When the engine is stopped close behind another train.
o 3. In non-signaled territory, when the engine is stopped on the main track waiting for an approaching train.
o 4. When approaching and passing the head end and rear end of a train on the adjacent track.
o 5. At other times to permit passing of hand signals or when the safety of employees requires.
• The opposite light should be dimmed.

DCC: (muss für US Z Lines angepasst und überarbeitet werden)
F0 controls front light, and F1 controls the rear. Since Rule 17 specifies behavior of both lights, it is clearly not compatible with directional lighting. If Rule 17 is enabled, the light opposite the direction of travel will be dimmed. An additional function (usually F4) will dim the light in the direction of travel.
There will usually be another CV to set the brightness of the dimmed light. This will usually require tuning, particularly in non-"plug and play" decoders as the duty cycle necessary to run a LED dim, will be different than that required by an incandescent bulb.
Some decoders will automatically dim when stopped, which is convenient if not exactly prototypical. Others require the use of F4.  

The dispatcher can run the train as an extra. This would require two orders, one annulling the trains schedule, second all effected trains must receive a copy of this order, both regular trains whose schedules have not completed and extras.  
When track is signaled in only one direction, signal indication will be the authority for trains to operate with the current of traffic. Movements made against the current of traffic will be governed by non-signaled DCS rules (see Rule 261: reverse movement beyond the limits of the block).

 
Rule 261: giving trains authority to move on signal indication in both directions
Signal indication will be the authority for a train to operate in either direction on the same track.
Rule 261: reverse movement beyond the limits of the block
Where Rule 261 is in effect, a train must not make a reverse movement beyond the limits of the block without verbal permission of the Dispatcher (or Operator when authorized by the Dispatcher). Before permission is granted, the Dispatcher must determine that:
1. The track to be used is clear of opposing movements,
AND
2. Signals governing opposing movements are in Stop position,
AND
3. Blocking devices are applied to protect against opposing movements.
Verbal permission to re-enter must be given in the following manner:

“No. 5306 engine 4129 reverse direction on No. 2 track at MP 5 and proceed west to MP 6.”

Movement must operate at Restricted Speed until governed by a more favorable signal.  
When a train or engine is to do work, or occupy track or tracks within specified limits, where Rule 261 [giving trains authority to move on signal indication] is in effect, permission must be obtained from control station, specifying time and limits, and tracks to be used. When the train or engine has entered these limits control station must lock all signals governing movements into such limits at “stop,” and locks must not be removed until the train or engine has cleared the specified tracks within the limits. Tracks specified may be used in either direction within the specified limits without flag protection.

Train or engine must be clear of tracks specified within the limits by the time stated and will report to control station when clear. When additional time is required, it must be authorized by control station before expiration of previous time limit.

Where the control station is not operated by train dispatcher, such permission, working limits, and specified tracks, must first be obtained by the control station from the train dispatcher.

From The Atchison, Topeka & Santa Fe Rules of the Operating Department, Revised 1959