AWS/TPWS

Question 1

when will you receive an AWS warning horn?

Answer 1

reduction in permissible speed ( a third of more 60-20 e.g )
TSR/ESR
Level crossings (AOCL,ABCL,OC
Every colour aspect (aside from green is bell)

Question 2

name the 4 types of track based equipment AWS? (magnets) and why they’re used

Answer 2

Permanent magnet (horn) x electro magnet (bell)
permanent magnet (horn) on its own

depot testing magnet (placed before main line on a depot)

suppressor magnet (used to when train going in wrong direction)

portable magnet (used over TSR/ESR)

Question 3

name all TPWS lineside equipment how it works and what it does ?

Answer 3

Train Stop System (TSS)
activated TPWS receiver on the train and activates brake demand
-energised when signal is at danger, deenergized when signal showing proceed aspect
arming and trigger loop are together

Over speed Sensor System (OSS)
always energized
causes brake demand if trains is speeding or approaching signal too quick or if approaching reduction in permissible speed too quick.
arming and trigger are separate there’s a timer that is used to measure speed

Question 4

tell me about the TPWS control panel what’s on there?

Answer 4

Train stop override button (square yellow button)
temporary isolation/fault (yellow circle indicator)
brake demand (red circle indicator)

Question 5

when would you press train stop override button?

Answer 5

where authority is given to PSAD. overrides bake demand from the TSS loop for approx 20 seconds (illuminate when used)

Question 6

when would Temporary isolation/fault be lit ?
or flashing?

Answer 6

lit - the train TPWS equipment has been temp isolated
flashing- a fault has been detected in the train TPWS equipment or the start up test has not been completed

Question 7

when would brake demand light up?
or be flashing ?

Answer 7

lit - brake demand has activated but been acknowledged by the driver
flashing - TPWS or AWS has initiated brake demand that has yet to be aknolwdged by the driver

Question 8

what is TPWS activation?

Answer 8

it’s when the driver applies the emergency brake before the TPWS interviens

Question 9

what is TPWS intervention?

Answer 9

this is when the driver does not iniate the brake TPWS has to intervien

Question 10

what are you to di upon receiving a wrong side failure?

Answer 10

report immediately, stopping to do so.

complete RT3185

Question 11

what are you to do if receive a right side failure?

Answer 11

report at first opportunity, complete RT3185

Question 12

what is the difference between a right side fissure and a wrong side failure ?

Answer 12

right side - where system has failed safe and you’d received a warning more restrictive than required

wrong side - where the system has failed safe and is giving less restricted warning than required

Question 13

does Isolating AWS affect TPWS?

Answer 13

yes it isolates them both

Question 14

does temp isolating TPWS affect AWS?

Answer 14

no

Question 15

what indication would you get if sat over an AWS magnet?

Answer 15

continuous warning horn that cannot be cancelled.

Question 16

what are your actions if you receive TPWS brake demand?

Answer 16

look at TPWS panel, acknowledge via AWS button to turn brake demand light to steady from flashing then put it into full service to prevent rolling when brakes release. contact signaller and act on instructions do not move train until authorised. brakes release after 60 seconds.