Signals Flashcards
What is the object of the Automatic Block Signalling (ABS) System and how is it achieved?
Where 2 or more trains are to proceed in the same direction:
Object | To prevent more than one train being in a track section at the same time
Achieved | By securing the fix signals at stop, unless the track section ahead is clear
On bi-direction lines:
Object | To prevent trains running in opposite directions in a single line section at the same time
Achieved | Signals controlled by the track circuit and display a Stop indication. Stopping a train from entering the single line section from the opposite end.
ABS operates either by track circuitry or axle counters
What are the station limits for ABS?
From the arriving home signal to the first automatic signal after the departing home signal.
Or
If thereβs no departing home signal. Itβs from the arriving home signal to the first automatic signal ahead.
What are the 2 types of ABS?
- Automatic Block Signalling - Double line
- Automatic Block Signalling - Single line
What is the object of the Automatic and Track Control System (ATC) and how is that achieved?
Two or More Trains in the same direction:
Object | Prevent more than one train being on a track section at the same time
Achieved | By fixed signals being controlled by track circuitry protecting the train in advance
Opposing direction movements:
Object | Prevent more than one train moving through the single line section
Achieved | By opposing departure signals controlling the entrance to the section, being secured at stop and unable to be placed at proceed while set for opposing movements
What are the Station limits for ATC?
The portion of line between opposing ATC Home Arrival signals.
3P
π’
π΄
Clear Normal Speed
P - Points are set
T - Track is clear
S - Track Speed
N - Next signal is a proceed aspect
3P
π‘
π΄
Normal Speed Warning
P - Points are set
T - Track is clear (until next fixed signal)
S - Track Speed but be prepared to stop
N - Next signal is at Stop
3P
π‘
π’
Reduce to Medium
P - Points are set
T - Track is clear
S - Track Speed but be prepared to reduce to 40km/h
N - Next signal is a medium aspect
3P
π΄
π’
Clear Medium Speed
P - Points are set
T - Track is clear
S - Max 40km/h
N - Next signal is a proceed aspect
3P
π΄
π‘
Medium Speed Warning
P - Points are set
T - Track is clear
S - Max 40km/h but be prepared to stop by the next fixed signal
N - Next signal is at Stop
3P
π΄
π΄
STOP
P - Points may or may not be set
T - Track may be occupied
S - STOP. Set reverser to OFF or controller to Neutral
N - Next signal is unknown
3P
π΄
π΄
π‘
Low Speed Caution
P - Points are set
T - May or may not be set
S - Max 15km/h but be prepared to STOP
N - Next signal unknown but will most likely be at STOP
3P Dwarf
π΄
π΅
π£
STOP
P - May or may not be set
T - May or may not be occupied
S - Stop. Set reverser to OFF or controller to Neutral
N - Next signal is unknown
**3P Dwarf **
π‘
Low Speed Caution
P - Points are set
T - May or may not be occupied
S - Max 15km/h but be prepared to stop
N - Next signal unknown but prepare to stop
3P Dwarf
π’
Clear Low Speed
P - Points are set
T - Track is clear to the next signal
S - Speed is Max 15km
N - Next signal is a proceed aspect
What are the Banner Indicators?
π’ = βͺοΈ
βͺοΈ
βͺοΈ
π‘ = βͺοΈ
βͺοΈ
βͺοΈ
π΄ = βͺοΈβͺοΈβͺοΈ