If the Cab Signal changes between fixed signals, the cab signal will govern, subject to the following restrictions:
1. Cab Signal changes to restricting
When the cab signal aspect changes to restricting between fixed signals, the Engineer must take action at once to reduce to Restricted Speed.
2. Interlocking Signal requires Medium or Limited Speed, Cab Signal changes to more favorable aspect
If an Interlocking Signal requires Medium or Limited Speed and the cab signal changes to a more favorable signal, the speed must not be increase until the train has run it's length.
3. Cab Signal changes from Restricting to more favorable
If the Cab Signal changes from restricting to a more favorable aspect, the speed must not be increased until the train has run it's length or 500 feet, whichever distance is greater
4. Cab Signal changes from Clear to Approach Medium
If the Cab Signal changes from Clear to Approach Medium between fixed signals, trains must immediately begin reduction to Limited Speed, and must further reduce to Medium Speed if the next signal is seen to display an aspect requiring Medium Speed.
EXCEPTION: If the Cab Signal does not conform to the fixed signal at the entrance to the block, and the fixed signal is more restrictive than the cab signal, the fixed signal will govern throughout the entire block
EXPLANATION: Rule 553 covers how a train will be governed once fixed signal and cab signal conformity exists after a train enters a block. If the cab signal conforms to the fixed signal upon entering the block, the Fixed Signal Governs, but if the cab signal changes between fixed signals, the Cab Signal Governs movement through the block, with 4 specific restrictions.
OF FIRST IMPORTANCE: If an Engineer cannot confirm conformity between the cab signal and the fixed signal after entering the block, the more restrictive of the two signals governs the train movement through out the block, And, as a reminder, if conformity does not exist for two (2) fixed signal locations in succession, then it is to be considered a cab signal failure per rule 555.
Rule Review
Rule 553, Cab signal changes between fixed signals:
When a cab signal changes to Restricting between fixed signals:
1. The engineer must dump the train.
2. The engineer must dump the train and
run back through the cars yelling: EMERGENCY, EMERGENCY, EMERGENCY!
3. The engineer must immediately reduce
speed to Medium speed.
4. The engineer must take action at once
to reduce to Restricted speed.
If an interlocking signal requires Medium or Limited Speed and the cab signal changes to a more favorable aspect:
1. The cab signal system has failed.
2. The engineer can ignore the cab signal
since the more restrictive indication applies.
3. Speed must not be increased until the
train has run it's length.
4. Speed can be increased as soon as the
more the cab signal indication changes.
If the cab signal changes from a Restricting to a more favorable aspect:
1. Speed cannot be increased until the
cab signal conforms to two wayside signals.
2. Speed can be increased as soon as the
cab signal indication changes.
3. Speed cannot be increased until the
train has run it's length or 500 feet, whichever is greater.
4. Speed cannot be increased until the
cab signal conforms to the next wayside signal.
If the cab signal changes from Clear to Approach Medium between fixed signals:
1. Trains must immediately reduce speed
to Restricting as there is no Approach Medium cab signal aspect.
2. Trains must immediately reduce speed
to Limited Speed and further reduce to Medium Speed if the next signal
displays an aspect requiring Medium Speed.
3. Trains must immediately reduce speed
to Medium Speed.
4. Trains may continue at Normal Speed
until the cab signal changes to Approach.
If the cab signal does not conform the fixed signal at the entrance to a block and the fixed signal is more restrictive:
1. The cab signal will govern movement
through the entire block.
2. The fixed signal will govern movement
until the cab signal conforms.
3. The fixed signal will govern movement
through the entire block.
4. The cab signal is considered failed
and the Dispatcher must be notified.