Signalling Flashcards
(20 cards)
What is the absolute block section?
The portion of the line that runs from the section signal of the signal box in rear to the first home signal of the signal box in advance.
What is the golden rule of absolute block signalling?
Only one train in one block section at any one time.
How far away is the distant signal from the first home signal?
Service brake distance. This isn’t a defined distance but a distance that ensures the train with the longest stopping distance will still have time to stop before the next signal.
What is permissive working?
When two or more trains are on the same portion of line, e.g. for coupling or assistance purposes.
How close to a stop signal should you stop?
No closer than 20 metres.
What is the station limit?
The portion of line between the first home signal and the section signal. There does not have to be an actual station in the area.
What does a white ID plate with a horizontal black stripe mean?
The signal is an automatic signal operated by the passage of trains.
What is a distant signal?
A signal that cannot show a stop aspect or indication. Some colour light distant signals are identified by a white triangle or the letters ‘R’ or ‘RR’ (outer distant) on the ID plate.
What is an intermediate block home signal?
A stop signal that controls the exit from an intermediate block section, and the entrance to an absolute block section ot another intermediate block section.
What does a white ID plate with a vertical black stripe mean?
The signal is an intermediate block signal.
What does a white triangle ID plate mean?
The signal is a distant signal (it can’t display a stop aspect).
What does the letter ‘R’ at the bottom of an ID plate mean?
The signal is an inner distant signal (it can’t display a stop aspect).
What do the letters ‘RR’ at the bottom of an ID plate mean?
The signal is an outer distant signal (it can’t display a stop aspect).
What is the normal sequence of three aspect signalling?
- Green (proceed)- the next signal will be displaying a proceed aspect.
- Yellow (caution)- proceed but be prepared to stop at the next signal.
- Red (danger)- stop.
What is the normal sequence of three aspect signalling?
- Green (proceed)- the next signal will be displaying a proceed aspect.
- Double yellow (preliminary caution)- proceed but be prepared to find the next signal displaying a single yellow aspect.
- Single yellow (caution)- proceed but be prepared to stop at the next signal.
- Red (danger)- stop.
What is a junction indicator used for?
To show that a train is being signalled to a route to the left or right of the straight route. It will display a line of 5 white lights when a proceed aspect is displayed.
When would a junction indicator be provided for all signalled routes?
When there is no obvious straight route.
What happens to a junction indicator if the straight route is not the highest speed route?
The junction indicator will normally apply to the lower-speed route.
What happens to a junction indicator when the diverging routes are of equal speed?
A junction indicator will be provided for each route.
What does a route indicator do?
It displays either a letter or a number to show the route onto which the movement is being signalled. Route indicators may also be associated with a junction indicator.
