Signalling and Dispatch Flashcards
(50 cards)
Where would you find information regarding the signalling system in place on your route?
Sectional Appendix
What is the principle of Absolute Block?
One train in one section at one time
What does a semaphore stop signal mean when it is in the horizontal position?
Stop or danger
What can a semaphore stop signal also be known as?
Home
What does a semaphore distance signal mean in the horizontal position?
Proceed with caution
What colour is a semaphore signal on the reverse?
Black and white
Draw Absolute Block?
Step 1: Draw Two Signal Boxes
Draw two small boxes on either side of your page labeled:
Signal Box A (left side)
Signal Box B (right side)
Step 2: Add the Track
Draw a single line (representing the track) connecting the two signal boxes.
Label this line “Single Line Track” or “Running Line”.
Step 3: Divide the Track
Divide the track between the two boxes into three sections:
Block Section (between A and B)
Use dashed vertical lines to mark the boundaries.
Label each section clearly.
Step 4: Add Signals
Near each signal box, draw Distan, Home and Section Signals:
At Signal Box A:
Distant, Home Signal (on the approach to the box)
Starting Signal (just before the train enters the Block Section)
At Signal Box B:
Same arrangement as A, but on the other end
Step 5: Indicate the Block Instruments
Draw a small train icon in one of the sections to demonstrate how the system works.
For example, place it in the Block Section, and label it “Train in Section”.
Why would a semaphore distant signal be positioned underneath a stop signal?
If there is a distant signal on the same post as a stop signal:
- the stop signal is worked by the signal box at that location and the
- distant signal is worked by the signal box ahead
And it’s usually done when there isn’t enough distance between the stop and distant
What does a diamond signal mean if attached to a signal post?
You are going into track circuit from absolute block
What does the term Intermediate Block mean?
IB creates extra section within absolute block allowing more trains on the line.
A section of track within a larger absolute block section where another train can be admitted, provided it’s clear of trains in the preceding section and the intermediate block itself.
What type of signal would you find in Intermediate Block?
In an intermediate block section, you would find intermediate block home signals and their associated distant signals.
These signals are typically color light signals
Can the distant signal be pulled off before the home and section signal?
No, the distant signal cannot be pulled off before the home and section signals.
The distant signal is designed to be “pulled off” only when the home and starting signals are also cleared, indicating a clear path for the train to proceed.
What is a Fixed Distant signal and where would you find it?
It is a distant signal that permanently displays a caution aspect, meaning it always shows a “caution” signal to drivers.
You might find Fixed Distant signals at the end of a single line, or at the approach to a terminal where the next signal is always at danger
What letters could you find on a subsidiary signal?
On subsidiary signals, you might find the letters C, S, or W.
These letters indicate different types of subsidiary signals:
“C” for Calling-on,
“S” for Shunt-ahead, and
“W” for Warning.
Draw a shunt signal in the STOP position?
Triangle (ish) box with bottom two lights red and white or both red
How do you read semaphore junction indicators?
The highest one indicates the route/line.
Semaphore junction indicators are supplementary signals used in semaphore signalling systems to indicate when a train is being routed to a side track, rather than the straight track
What is the principle of Track Circuit Block?
One train in one circuit section at one time
Draw the sequence of a four aspect signal starting with green.
Green, double yellow, yellow, red
What is an IBJ?
Insulated block joint - used to detect the presence of trains on a section of track. By electrically isolating sections of track, track circuits can accurately determine if a section is occupied. Thus changing the signal.
What sign is under an automatic signal?
A white box with a horizontal black line
What sign is under a semi automatic signal?
A white box with a horizontal black line with semi written above the line
What sign signifies the Intermediate Block home signal?
A white box with a vertical black line running through it
What does a white triangle mean on a signal?
It’s a distant signal
What is a ground position light?
A signal used to control shunting movements, typically near points and sidings
