AB/TCB signalling

Question 1

what is an absolute block section?

Answer 1

a block of line where only one train at any one time can enter

Question 2

what is service braking distance ?

Answer 2

measured from worst performing train in that areas stopping distance. there in case a spad

Question 3

what are IB signals?

Answer 3

track circuited, a IBH includes a SPT and must have an ID plate

Question 4

why was Intermediate block areas created?

Answer 4

to increase amount of trains between block sections and fill big gap areas

Question 5

who controls Intermediate block areas?

Answer 5

the signaller in rear

Question 6

what is Track circuit Block signalling ?

Answer 6

signalling where track circuits control the block section, signals can clear automatically when a block ahead is proved clear and return to danger when occupied

Question 7

what is a IBJ (insulated block joint) what does it do and where are they?

Answer 7

IBJ acts like a treadle there’s always 2x one at the signal and one at the overlapping distance , detects train and reverts passed signal to danger and signals in rear to yellow etc depending on aspect signalling.

Question 8

what are the overlapping distances for the IBJ at 2/3/4 aspect sognallling ?

Answer 8

the first IBJ puts the signal you’re on to DANGER, once passed the overlapping IBJ it changes it to single yellow

2 aspect signalling 400 yards
3 aspect signalling 300 yards
4 aspect signalling 200 yards

Question 9

what is an Outer distant signal ?

Answer 9

it’s used to increase service braking distance usually if line speed has changed