Automatic Warning System

The Automatic Warning System (AWS ) is a train control system, which comes in the UK since 1956 for use. In 1992 were equipped with it about 11,000 km ( about 16,000 kilometers of total ) of the route network of British Rail.

Operation

About 180 meters in front of a distant signal or the announcement of a speed restriction is centrally located in the track a so-called AWS ramp. It comprises a permanent magnet and a reverse polarized electromagnet; with announcements of speed restrictions, the solenoid is not necessary.

Under the vehicle, a receiver is installed which reacts to these magnetic fields. In the cab there is a bell and a horn (today these sounds are often generated electronically ), an indication of the device status, as well as a confirmation button ( vigilance ).

If the distant signal " ride free" shows the solenoid is activated. This means that in the cab will sound the bell and the display is black.

However, if the distant signal " expect danger " displays ( and always in the case of speed limitations), the solenoid is not active or not available. In this case, the horn sounds. The driver now has two to three seconds of time to serve the vigilance. If he fails to do so, the emergency brake.

With timely operation of the vigilance silenced the horn, and the display becomes a pattern of alternating yellow and black sectors ( colloquially called "Sunflower "). This reminds the driver because he has received a warning and confirms this. It is now his duty to initiate the braking. However, this is not monitored by the Automatic Warning System.