Working of Single Lines Flashcards
(14 cards)
What two things are needed to keep single lines safe?
A signal and a something.
Explain how electric token block signalling works.
- Driver arrives at signal box A.
- Signaller A communicates with Signaller B to ensure the absolute block section is clear.
- Signaller A dispenses a brass key from the electric token machine (which locks the tokens in signaller B’s machine) and gives it to the driver.
- Driver checks the key is the correct one for their route and proceeds through the absolute block section.
- Driver arrives at signal box B and returns the key to signaller B.
What type of signalling is electric token block?
Absolute block signalling.
Explain how no signaller token block signalling works.
- Driver arrives at signal box A.
- Signaller A dispenses a brass key from the electric token machine and gives it to the driver.
- Driver checks the key is the correct one for their route and proceeds through the absolute block section.
- Driver arrives at the electric token machine and calls Signaller A for permission to return the token.
- Driver returns the token and asks for permission to take another token from a second machine to proceed on their journey.
Explain how one train working with staff works.
The staff is an object stored in a locked cupboard that authorises the driver that possesses it to proceed. There is only one staff, therefore the driver in possession is protected as no other train can proceed without it.
When can you travel on a single line without a token/staff?
Possession (engineers’).
Assist a failed train.
Modified working arrangements.
Pilot working.
Shunting purposes (on an ET line).
What should you do if a signal failure occurs at the entrance of a track circuit block single line?
Ask the signaller if the track circuits are operational and if they’re clear. If the answer to either is no, a P.I.L.O.T. will be required.
What is a P.I.L.O.T.?
Person in lieu of possession. This person acts as a token, whereby trains travelling on single lines gain authorisation to do so by having the P.I.L.O.T. travel on their train. Once the train reaches the end of the single line, the P.I.L.O.T. deboards and boards another train travelling back to point A.
Explain how one train working without a staff works.
The section of the line concerned will not be track circuited, therefore when a train enters, the signal in rear will revert to red and the train will ‘drop off’ the track circuit system, with the signal remaining at red until the train leaves.
Where should the token or staff be kept whilst in your possession.
In the leading cab.
When the single line is in the possession of engineers, who is in possession of the token?
The signaller keeps hold of the token in their electric token machine whilst engineering work is being carried out.
If a failed train on a single line is being assisted, who should be in possession of the token?
The driver of the failed train should keep the token but show it to the driver of the assisting train. The key must be stored in the leading cab even if the movement of the train is being controlled elsewhere.
What should you do with your train’s tail lamps if it fails on a single line?
If in an ABS area, you shouldn’t illuminate your train’s tail lamps until you’re in view of the signal box as you need to make them aware that your train isn’t complete. If in a TCB area, you can put the tail lamps on immediately as the track circuits will inform the signaller where the rest of the train is.
What is modified working?
Form RT3177 acts in lieu of a token to allow a train to proceed onto a single line before a P.I.L.O.T. has arrived. You must complete the form with the signaller in order to gain authorisation to proceed.
