It is made with electric plate peizo. It converts mechanical vibration into electrical signal. The output of the vibration sensor is given to the amplifier to amplify that electrical signal.
The amplified signal is then given to the microcontroller. And we have a transmitter and a receiver both are connected with the cables. These are closely linked to the track, if the track is cut, this cable will also be cut.
In real time we have this vibration sensor, transmitter and receiver on track for every 200 meters. Or we can extend this distance using amplifiers. When the train enters the track, the vibration sensor detects the vibration of the train and sends a low pulse to the microcontroller.
Whenever the controller detects a low pulse from the sensor, it will send a check data to the receiver from the transmitter. If the receiver receives the signal without loss means, the receiver sends a high pulse to the controller and then identifies that the track is good.
If the receiver did not receive the signal means, the controller will send a warning SMS to the mobile receiver, which is on the train, through the mobile transmitter, which is interconnected with the microcontroller.
The RS232 is used to communicate the controller and the mobile. So the accident can be avoided. When the workers go to work on the track means that they will press a key, which is interconnected with the microcontroller. The controller will then send an alert SMS to the receiving mobile. Before this we have to program the microcontroller for this application.
Following video is better to understand the Security System For Railway Tracks Using GSM Communication: