AWS Flashcards
What is AWS?
Automatic warning system.
When was AWS implemented?
1950’s.
What is the purpose of AWS?
It provides the driver with an audible and visual indication of whether the distant signal is clear or at caution.
What would happen if the driver failed to respond to a warning indication?
An emergency brake application will be initiated.
What does the AWS consist of?
Train and track equipment.
How far is the AWS magnet normally placed on the approach to a signal?
180 meters (200 yards)
How does the AWS system work?
The train detects sequences of magnetic fields passing between the track and the train equipment via a receiver under the train.
Where may AWS track equipment not be provided?
At through stations where the permitted speed is 30 mph or less and the layout is complex.
When this occurs, what is it called?
An AWS gap.
At what type of stop signals is AWS not provided?
Semaphore signals.
What semaphore signal is provided with AWS?
The distant signal when it is mounted on the same post as a semaphore stop signal.
Where can you find information on where a line is not fitted with AWS?
The sectional appendix.
Aside from signals, what do AWS magnets alert the driver to?
Level crossing warning boards or indicators
Temporary speed restriction warning boards
Emergency speed restriction warning boards and indicators
Where is AWS mounted?
In the four foot.
What type of magnet will the train first encounter?
A permanent magnet.
What type of warning does the permanent magnet give?
A warning indication to the driver.
What magnet comes after the permanent magnet?
An energised electromagnet.
What indication does the electromagnet give the driver?
A ‘clear’ indication when approaching a signal or a semaphore distant
signal showing ‘clear’.
What does the AWS receiver detect?
Detects the sequences and polarities of magnetic fields from the AWS
track magnets.
What does the audible indicator give?
Gives a warning or clear indication.
What are the types of AWS warning indicators?
A clear indication (bell)
A warning indication (horn)
What does the black indicator (in the cab) mean?
It advises the driver that the associated signal is showing a green aspect or ‘all clear’.
What else does it advise the driver?
It advises the driver that the audible warning has not been acknowledged.
What does the yellow and black indicator (in the cab) advise?
It advises the driver that a warning indication has been acknowledged.
What will be applied if the driver fails to acknowledge the AWS warning
indicator?
The brakes will be applied (emergency).
What is the purpose of the AWS/TPWS acknowledgement button?
It is used to acknowledge an AWS warning.
How much time does a driver have to acknowledge the AWS warning?
Two to three seconds (2.7).
If there is a fault with the AWS, how many fault indicators does the
AWS have?
Three indications.
What colour are the AWS isolation/fault indicators?
Yellow.
If the AWS indicator light is off, what state is this?
Normal.
If the AWS light is flashing, what state is this?
A fault has been detected in the train AWS equipment.
If the AWS light is on (steady), what state is this?
The train AWS equipment has been isolated.
When will the driver receive a warning indication?
On the approach to a colour light signal displaying a single or double yellow or a red aspect.
Semaphore distant signal displaying a caution indication.
Warning indicator provided for some permissible speed reductions.
Warning board provided for ABCL, AOCL or OC level crossings.
Warning board or emergency indicator for a TSR or ESR.
Cancelling indicator for an AWS warning which does not apply to the train.
AWS is capable of distinguishing between a red, double yellow or single aspect. True or false?
False.
The driver will receive a clear indication in the driving cab when approaching:
A colour light signal showing a green aspect.
A semaphore distant signal displaying a clear indication.
The driver does not have to acknowledge a clear indication. True or false?
True.
In some AWS fitted areas, AWS equipment is not provided throughout. How are these areas identified?
They are identified with signs.
What are the signs for the start of the AWS gap?
A white circle with AWS written in black letters and a red cross through it.
What are the signs for the end of the AWS gap?
A white square with the letters AWS written inside of it.
On single and bi-directional lines, what normally happens to the AWS magnet?
It is normally suppressed for movements to which it does not apply and the AWS will not operate.
Where the AWS magnet is not suppressed, what indicator is provided?
A cancelling indicator.
What does the cancelling indicator advise the driver?
It advises that the indicator does not apply to trains travelling in that direction.
Where the AWS magnet is permanently installed, what does this sign look like?
Blue square with a white cross inside of it.
Where the AWS magnet is provided in connection with a temporary or emergency speed restriction?
A yellow square with a black cross inside of it.
At what distance is the cancelling indicator normally positioned?
180 meters (200 yards)) after passing over the AWS magnet.
