AWS Flashcards
What is the purpose of the Automatic Warning System (AWS)?
The AWS provides audible and visual indications to the driver regarding the status of signals/reductions in permissible speed. If the driver fails to respond to warnings, an emergency brake application will be initiated.
What components make up the AWS?
AWS consists of both track and train equipment.
What is the function of the AWS magnet?
The AWS magnet is placed 180 metres from a signal to provide you with a warning of a change of aspect head.
Where are AWS magnets not provided?
AWS magnets are not provided at semaphore stop signals, only at semaphore distant signals.
What are the types of track equipment used in AWS?
The types of track equipment include permanent magnets, electromagnets, suppressor magnets, depot test magnets, and portable magnets.
What does the receiver in the train equipment do?
The receiver detects sequences and polarities of magnetic fields from the AWS track magnets.
What does the audible indicator do in the AWS?
The audible indicator provides a bell sound if clear or a horn for warning indications.
What is indicated by an all-black visual indicator in the cab?
An all-black visual indicator means the associated signal is displaying a green aspect.
What happens if the AWS audible warning is not acknowledged?
If the AWS audible warning is not acknowledged within 2-3 seconds, an emergency brake application will occur.
How is the absence of AWS indicated in certain areas?
The absence of AWS is indicated by specific signage showing the start and end of AWS gaps.
What must be done if the AWS is defective before starting a journey from a maintenance depot?
A train must not start a journey if any cab required to be driven has a defective AWS.
What should be done if the AWS becomes defective during a journey?
The train must be stopped immediately, the signaller must be informed, and no movement should occur until instructed.
When can the AWS be isolated during a journey?
The AWS can be isolated only when cancelling the warning does not stop the horn or brakes from applying.
What are the speed restrictions if the AWS is defective or isolated?
Freight trains and OTMs can proceed at a speed not exceeding 50mph; all other trains can proceed at a speed no more than 60mph without a competent person. With a competent person it is line speed. Poor visibility means 40mph
What is the distance for placing an AWS magnet when speed reduction is required?
An AWS magnet is provided 180 metres away from the warning indicator if a permissible speed over 60mph needs to be reduced by more than a third.
What additional warnings can AWS provide?
AWS can warn drivers of level crossing warning boards, temporary speed restrictions, and emergency speed restriction warning boards.
What is a permanent magnet in AWS?
The train first encounters a permanent magnet, which gives a warning indication if an electromagnet is not provided or not energised.
What does an energised electromagnet indicate?
An energised electromagnet gives the driver a ‘clear’ indication when approaching a green signal or a semaphore distant signal showing ‘clear’.
What is the purpose of a suppressor magnet?
Suppressor magnets suppress permanent magnets when they are not required for a train movement in that direction of travel.
What is a depot test magnet?
A depot test magnet is a permanent magnet located at depots used to test the operation of a train’s AWS.
What are portable magnets used for?
Portable AWS magnets provide warnings to the driver on the approach to temporary and emergency speed restrictions.
What does the audible indicator do?
The audible indicator makes a bell sound if clear or a horn to provide a warning indication. The driver does not have to acknowledge a clear indicator.
What does the yellow and black indication advise the driver?
The yellow and black indication advises the driver that a warning indication has been acknowledged.
What is the purpose of the AWS/TPWS acknowledgment button?
This button is used to acknowledge an AWS audible warning. If it is not pressed within 2-3 seconds of an audible warning, then an emergency brake application will occur.
