Types of Single Lines

Question 1

What are single lines?

Answer 1

Portions of bi-directional line where only one train can be in one section at one time

Question 2

Where are single line locations found?

Answer 2

In the Sectional Appendix

Question 3

How do TCB single lines work?

Answer 3

By track circuits that detect trains and determine if the line is occupied

Question 4

If track circuits are unoccupied on a TCB single line, what does this mean for the direction flow indicator on TCB single lines?

Answer 4

The direction flow indicator is set to the direction of travel and sets all signals for trains joining the single line. This means that signals in the opposite direction will not operate.

Question 5

At what point can the signal protecting the single line clear on TCB single lines?

Answer 5

Once the occupying train leaves by passing the final signal, then another train can enter the single line.

Question 6

What happens if the track circuits/direction flow indicators are defective on TCB single lines?

Answer 6

You cannot prove the single line is safe. Signals revert to danger and a pilot is required as the usual token is track circuits.

Question 7

What happens if the signal protecting a TCB single line is defective but the track circuits and direction flow indicator are working?

Answer 7

Can prove the single line is unoccupied and you can be authorised to PSAD.

Question 8

What is your authority to enter a TCB single line?

Answer 8

Proceed aspect only

Question 9

What type of lines can Electric Token Block be used?

Answer 9

AB single lines

Question 10

How does electric token block work?

Answer 10

Token dispensed from machine at signal box A to be carried on single line and returned to Signal Box B’s machine when finished on single line. Once token is received by driver, signaller can clear the protecting signal.

When the token is returned, a new train can release a token and enter the single line.

Question 11

What happens if the signaller clears the protecting signal but the driver does not have the token on electric token block?

Answer 11

The driver does not have permission to proceed onto the single line. This is a SPAD

Question 12

If there are separate sections of single line operated by electric token block, what might be required?

Answer 12

A new token

Question 13

What happens on electric token block lines if there is no token available?

Answer 13

A pilot is required in lieu of the token

Question 14

What is your authority to enter an electric token block single line?

Answer 14

Proceed aspect and possession of the correct token

Question 15

How does a tokenless block single line operate?

Answer 15

There are track circuits at the entry and exit to the single line but not on the single line itself. Cameras confirm if line occupied and confirm that complete train leaves.

Question 16

What is your authority to enter a tokenless block single line?

Answer 16

Proceed aspect due to clear track circuits and cameras

Question 17

Can you be authorised to PSAD that protects a tokenless block single line?

Answer 17

No as there is no way to prove that the single line is safe. Pilot working must be introduced.

Question 18

Where is one train working with staff usually found?

Answer 18

On dead end single lines

Question 19

How does one train working with staff work?

Answer 19

A wooden staff is used as the token and is given to one train that occupies the single line. This staff must be returned to the original signaller after changing ends and returning

Question 20

What is your authority to enter a one train working with staff single line?

Answer 20

Proceed aspect and staff (may also be stop board with instructions that must be completed before entering single line).

Question 21

What is one train working without staff?

Answer 21

Where there is no staff but track circuits ‘lock’ you onto the line until the occupying train is detected leaving the single line- once this train leaves, you may enter.

Question 22

What do one train working without staff single lines always have?

Answer 22

An entry and exit signal. Once the exit signal is cleared, the entry signal can clear.

Question 23

What is your authority to enter a one train working without staff?

Answer 23

Proceed aspect only.

Question 24

In what circumstances is a token not required to enter a single line?

Answer 24

P- line under possession
A- assisting a failed train (REAR)
M- Modified working in operation
P- pilot working in operation
S- Shunting purposes

Question 25

Why do you not need a token if you are assisting a failed train?

Answer 25

The failed train already has this

Question 26

Why do you not need a token if pilot working is in operation?

Answer 26

The pilot is in lieu of the token

Question 27

Why do you not need a token if modified working is in operation?

Answer 27

The modified working ticket is the token

Question 28

Why do you not need a token if shunting?

Answer 28

The single line may be occupied so there is no token available and you may be authorised to pass the protecting signal at danger to access a siding.

Question 29

Why do you not need a token if entering a line under possession?

Answer 29

The token will be with the train in the possession. You may be authorised to pass the protecting signal at danger and without the token to access a siding before the possession.

Question 30

When you receive a token, where must this be kept?

Answer 30

In the leading cab until needed by a shunter

Question 31

If you give your token to a shunter, when can you continue your journey?

Answer 31

When the shunt is completed, when the points are locked in the correct position for trains to pass on the single line and when the shunter has returned the token to you.

Question 32

If you are an assisting train, will you receive a token and why?

Answer 32

No as the failed train already has the token.

Question 33

If your train divides on a single line and part of the divided train will remain on the single line, at what point can you put tail lights on the remaining portion of train?

Answer 33

After informing the signaller first as the signaller may think this is a complete train.

Question 34

What must happen to the token if the train is to be driven from other than the leading cab?

Answer 34

The token must be shown to the assisting driver and kept in the leading cab.