AWS
Automatic Warning System
Classic British warning system featuring track magnets, the famous cab sunflower, and audible horn/bell.
Easy
Based on vigilance required, reaction window, and braking penalty severity.
menu_book System Overview
AWS has protected British railways since the 1950s. Mounted approximately 180 meters before every main signal and permanent speed reduction, a pair of permanent and electromagnets test driver vigilance.
settings How It Operates
- check_circle Passing a Clear (Green) signal produces a clear bell chime in the cab; the visual sunflower indicator turns all-black.
- check_circle Passing a Caution (Double Yellow, Yellow) or Danger (Red) signal sounds a loud horn or buzzer tone.
- check_circle The driver must press the AWS Reset button within 2.5 to 3 seconds.
- check_circle Acknowledging silences the horn and turns the visual indicator into a black-and-yellow spoke ("sunflower"), serving as a continuous visual reminder.
- check_circle If not acknowledged within 2.7 seconds, emergency brakes apply automatically.
visibility In-Cab Visual & Audio Indications
Circular visual display: all black after green signals; alternating yellow and black spokes after restrictive warnings.
Clear bell or electronic chime on green signals (no action required).
Loud horn or warning tone on caution/stop signals (requires acknowledgment).
lightbulb Driver Tips to Avoid Penalty Brakes
- verified Never cancel AWS without mentally registering why it triggered (did you just pass a single yellow or a speed reduction warning?).
- verified Combine AWS with TPWS for full British route protection.
