Aws Flashcards
What is the purpose of AWS?
AWS provides the driver with an audible and visual indication of whether the distant signal is clear or at caution.
Since the introduction of multi-aspect signalling the majority of signals are now fitted with AWS
Briefly describe AWS provision
Track and train equipment
Track - AWS magnet 180m on the approach to a signal
Train - receiver under train, audible and visual indicator in cab, acknowledgement button and an isolation/ fault indicator
Describe the visual AWS indicators
What are the five pieces of AWS track equipment?
Permanent magnet
Suppressor magnet
Electromagnet
Depot magnet
Portable magnet
What does AWS stand for?
Automatic Warning System
What is the purpose of AWS?
To alert the driver to the status of upcoming signals or speed restrictions
What does a driver hear when approaching a signal showing green?
A bell sound from the AWS unit
What does a driver hear when approaching a signal at caution or a speed restriction?
A warning horn
What must a driver do after hearing the AWS warning horn?
Acknowledge it by pressing the AWS cancel button
What happens if the driver does not cancel the AWS warning in time?
An automatic brake application is triggered
What is the typical time allowed to cancel the AWS warning?
About 2–3 seconds (varies slightly depending on system)
What happens if a driver cancels an AWS warning but then passes a signal at danger?
The AWS system does not prevent SPADs—it is advisory, not interlocking
Where are AWS magnets usually located?
On the track between the rails before a signal or speed restriction
What is a permanent AWS magnet?
A magnet that gives a warning regardless of the signal aspect—used for speed restrictions
What is a suppressor magnet?
A device that cancels the warning horn if the signal is showing green
What does it mean if a signal has an AWS magnet but gives a horn even when green?
It may be a permanent AWS magnet for speed restrictions or special conditions
What should a driver do if the AWS warning does not match the signal aspect?
Report the irregularity to the signaller immediately
What should a driver do if AWS equipment on the train is faulty?
Report it and follow local rules for AWS isolated or failed trains
What is the AWS sunflower?
A visual indicator in the cab showing whether the system is in a warning or clear state
What does the AWS sunflower show after cancelling a warning?
Black and yellow spokes, indicating a warning was received
When is the AWS system tested?
During daily preparation and when entering a new train cab
Can AWS be isolated by the driver?
Yes, but only with authority and according to company rules
What does AWS NOT protect against?
It does not prevent SPADs, overspeeding, or ensure braking—it only warns the driver
Why is AWS still important even with modern systems like TPWS or ETCS?
It provides a basic level of signal awareness and backup safety
