B - Other Issues, Signalling and Control

Question 1

How do control boxes know where trains are?

Answer 1

Track circuit
If a train is on a certain section of track the train will short circuit the circuit and so a red light will appear
This means if the circuit breaks it will also have a red light

Question 2

What is 2 Aspect signalling?

Answer 2

Simplest form with a red and green light

Only works if the train is slow enough that allows it to stop in the distance of the driver seeing the light

Question 3

What is 3 or 4 Aspect signalling?

Answer 3

Green - continue at normal speed
Double yellow - proceed with caution at reduced power
Single yellow - power off, control breaking
Red - stop

Allows the track to be divided into short blocks giving good control and minimising distance between trains

Question 4

What now supports the signalling system?

Answer 4

In-cab warning devices

Automatic breaking systems linked with signals

Question 5

What is headway?

Answer 5

The time interval between the back of one train and the front of the next

Question 6

What is an automatic warning/breaking system (A Balise)?

Answer 6

Inductive coils which understand the signals

Which then give a warning to a driver and can implement emergency breaking if no action is taken

Question 7

What are the three levels of European Train Control System (ETCS)?

Answer 7

1 - conventional system with automatic breaking
2 - signals in cab only, trains in constant communication with radio block centre, some locations still controlled by track circuits
3 - everything done by radio communication, no need for fixed blocks or track circuits

Question 8

How is the system safe from interlocking routes?

Answer 8

It is unable to set unsafe combinations of signals and switches