Absolute Block

Question 1

What is the principle of Absolute Block? TS3-2 (1)

Answer 1

The principle of the absolute block system is to prevent more than one train being in a section on the same line at the same time.

Question 2

What is the definition of an Absolute Block section? TS3-1 (1)

Answer 2

The line between the last stop signal (section signal or IBH signal) controlled from one signal box, and the home signal controlled by the next signal box.

Question 3

What is the definition of Station Limits? NOI-24 (1)

Answer 3

The line between the home signal and the section signal worked by the same signal box and in the same direction of travel.

Question 4

What is the definition of an Intermediate Block section? TS3-1 (1)

Answer 4

The line between the section signal and the intermediate block home signal worked by the same signal box in the same direction of travel.

Question 5

What is the definition of a clearing point? TS3-1 (1)

Answer 5

The point beyond the home signal up to which the line shall be clear before a signalled running movement can approach the home signal as shown in regulation 3.4.

Question 6

What is the definition of a home signal? TS3-1 (1)

Answer 6

The first stop signal controlled by a Signal Box that controls the exit from an absolute block section.

Question 7

What is the definition of a section signal? TS3-1 (1)

Answer 7

A stop signal that controls the entrance to an absolute block section or an intermediate block section.

Question 8

What is the definition of an intermediate block home signal? TS3-1 (1)

Answer 8

A stop signal that controls the exit from an intermediate block section, and the entrance to an absolute block section.

Question 9

What two distances are associated to a clearing point, and what decides the distance? TS3-3.4.3 (2)

Answer 9

Semaphore distant signal: 400 metres/440 yards beyond home signal.
Colour light distant signal: 183 metres/200 yards beyond home signal.

Question 10

What is the allocated distance for braking distance between the distant signal and the home signal? (1)

Answer 10

Suitable braking distance.

Question 11

What are the seven bellcodes that are used that don’t require call attention first? TS1-2 (7)

Answer 11

Train entering section: 2.
Restricted acceptance: 3-5-5.
Obstruction danger: 6.
Police assistance: 1-1-6.
Pick up telephone: 1-2.
Proceeding without authority in RIGHT direction: 4-5-5.
Proceeding without authority in WRONG direction: 2-5-5.

Question 12

Bellcode for train class…? TS1-2 (11)

Answer 12

Class 1 : 4
Class 2 : 3-1
Class 3 : 1-3-1
Class 4 : 3-1-1
Class 5 : 2-2-1
Class 6 : 5
Class 7 : 4-1
Class 8 : 3-2
Class 9 : 1-4
Class 9 Empty Coaching Stock :1-4-1
Class 0 : 2-3

Question 13

What criteria must be met before offering a train to the Signal Box in advance during normal method of signalling? TS3-3.1.1 (2)

Answer 13

2-1 must have been received for the previous train.

Block indicator must be at normal.

Question 14

At what point must you send train entering section to the advance Signal Box? TS3-3.1.1 (2)

Answer 14

When the train passes the Signal Box.

Or, the location shown in the Signal Box Special Instructions.

Question 15

Do you need to observe the train’s tail lights before you send train entering section? (1)

Answer 15

No.

Question 16

If there is an intermediate block home signal, when may you clear the section signal for a train to enter the intermediate block section, before offering the train on to the Signal Box in advance? TS3-3.1.4 (1)

Answer 16

As long as the line is clear up to and including the overlap track circuit beyond the intermediate block home signal.

Question 17

If a train is beyond your Signal Box before it has been accepted by the Signal Box in advance, and you have an intermediate block home signal, when do you send train entering section? TS3-3.1.4 (2)

Answer 17

Once the train has been accepted by the Signal Box in advance.
Once the intermediate block section has been cleared.

Question 18

At what point can you send train out of section after you’ve observed the tail lights on the back of the train? TS3-3.2 (3)

Answer 18

When the train has gone beyond the clearing point.
When the train has passed beyond a facing junction and you have the points for another line which is clear to the clearing point of that line.
When the train has been shunted clear of the running line.

Question 19

Before allowing a train to approach from Signal Box in rear, you must make sure… TS3-3.4.1 (4)

Answer 19

The line, or at a facing junction the line for which the facing points are set, is clear up to and including the clearing point.
All points within the clearing point have been set for the safety of the approaching train.
No conflicting movement has been authorised that will cross or foul the line within the clearing point.
No train has been accepted from another direction that requires a portion of the same line within the clearing point for acceptance.

Question 20

You must not allow the clearing point to be obstructed for a train that has been accepted, unless… TS3-3.4.2 (4)

Answer 20

The train has been stopped at the home signal.
The train has passed beyond any points or crossings that you need to use within the clearing point.
You have received cancelling for the train.
The train has failed.