Actually i want to place a pressure or Vibration sensor under the track so that when a train came over it then it produce a signal and this signal is sent to microcontroller then close the gate.
IR transmitter and Receiver can not be used because there willbe chance of error such as long animal (like giraffe) can also generate an interrupt signal and close the door.Pressure sensor is more accurate and error free because pressure sensor can be optimized to sense certain range of weight. What you think about my problem and what could I choose as a sensor to detect Train.