How does a train activate the signals at an intersection?

Question

Is there something on the ground that when a train goes over it activates the signal, or is there in the train?

Answer 1

there are beacon type object mounted on poles that are a certain distance from a crossing. the front of the train also has one mounted on it to give off a signal to make the lights and gates activate. once the train passes there is a beacon on the back of the train telling the crossing he train has passed

Answer 2

The train tracks and the train's wheels or rollers (whatever they are called) have a magnetic field or something causing the signals to activate.

Answer 3

teh driver presses a botton that activates it.

Answer 4

The two rails are made up one side positive and one side negative (low voltage).  When the train gets to a certain point (distance may vary depending on the crossing) the wheels complete the current and activates the signals.

  To prove this and I don't encourage it (disclaimer) take two clothes hangers and untwist them and stretch then out and twist the two together stretch it across the tracks near a signal and watch what happens! They will activate....Once again I do not encourage you to do this, but it will prove my point! Very against the law!!

Answer 5

near the intersection there is a point that when the two rails are connected the lights come on . the train acts as the connection . kids stupid ones sometimes put a metal bar across the tracks and leave it there this makes the lights come on and the bars go down.

Answer 6

The steel wheels and axles complete a simple circuit,  if you should ever walk down some old abandoned tracks you will see at a given point from the crossing gate an insulator between the sections of track of one of the two rails.  When the train wheel passes over this insulator it bridges the circuit and activates the mechanism.

Answer 7

In India, there are special wires connected to the rail track near the signals, and when a train passes over, the circuit trips and the signal activates.

It is reset remotely by the controlling cabin.

Answer 8

there are censers on the rails before a high way cross over so if the train is going 35mph that the arms and alarms will sound so the train doesn't stop and traffic does