General And AB Flashcards
(21 cards)
How many types of Signalling do we use on the Northern Network?
Three.
- Absolute Block
- Track Circuit Block
- Electric Token Block
Purpose of Signalling?
• to prevent conflicting movements
• regulate speed
• increasing line occupancy
• to indicate a change of direction
• for shunting
What signals would conductors need to read at the end of platforms?
They would need to be able to read the signal and the relevant junction indicator with that signal.
What is it know as if a conductor dispatches on a RED signal?
Starting against Signal, Signal Passed At Danger (SAS-SPAD)
Absolute Block Signalling: What is the principle?
One train in one section at one time.
What type of signal is usually found in Absolute Block areas?
Semaphore Signals
What does a Distant Semaphore Signal mean in both the horizontal position, and then with the arm angled at 45 degrees?
Horizontal: Caution - be prepared to stop at the next stop signal or any other stop signals controlled by that signal box.
Arm at 45 degrees: All associated stop signals at proceed aspect so proceed at normal speed.
What does a Stop Semaphore Signal mean in both the horizontal position, and then with the arm angled at 45 degrees?
Horizontal: Danger - Stop. (Also known as the Home or Section signal)
Arm at 45 Degrees: Clear - Proceed.
What is Absolute Block signalling divided into?
Block Sections. These begin at the Section Signal and end at the next home Signal.
What is in between Block Sections in AB?
400m clearing distance after the home signal and the entire distance between the home and section signal is know as Station Limits
In AB, what is the space between the distant and home signal known as?
Service Breaking Distance
What is Intermediate Block?
Because within AB, only one train could be permitted in one section at one time, the amount of trains running between a section could be limited. To combat this and increase train frequency, intermediate block was introduced.
This system works by putting a TCB distant and a home signal inbetween an absolute block section. This is then known as the Intermediate Block Section.
Which signal box would control Intermediate block? Box A or Box B?
Box A.
What are Subsidiary Signals?
It is a smaller arm of a semaphore stop signal positioned below the main arm. It gives the driver information on how to proceed.
What does a subsidiary signal in the horizontal position mean?
Means obey the main arm - Stop - Danger.
What does a subsidiary signal raised at 45 degrees mean?
It means pass the main arm at danger - proceed at caution toward the next train, signal or buffer stop but be prepared to stop short of any obstruction.
They can have a C or an S on them.
C: Calling on - proceed at caution as line ahead is occupied
S: Shunt - proceed at caution to carry out a shunt movement.
Shunting Signals - Red Aspects - give the meaning of the horizontal red bar and the red bar raised at 45 degrees?
If a shunting signal has a red bar in a horizontal position, it means STOP - Danger
If a shunting signal has a red bar raised at 45 degrees it means: proceed at caution as far as the line is clear.
What colours are the rear of Semaphore signals?
Black & White
In the case where a stop and distant signal are found on the same post - which signal box would control each?
The stop signal is controlled by the box at that location, the distant signal is controlled by the box beyond.
Where would you find a fixed-distant signal?
Locations such as loops or dead-ends - it means be prepared to stop at the next stop signal because there will definitely be one.
Semaphores - how would you be able to indicate a route?
With Semaphores, route indicators are stepped or stacked semaphore stop signals.
Stepped means the highest signal relates to the main route, and lower signals relate to the left or right of the main route.
With stacked, the highest signal is furthest left and then they progressively go to the right.
