how do trains trigger railroad crossing signal

There is an electrical connection from a rail to the signaling device that the locomotive completes when it approaches. It is low voltage for the safety of those that might contact it.

it has to do with the electrical current that runs across the wheels of each side of the train if u take a long piece of wire & touch each side of the rails this will cause the rails to come down l dont recomend doing it if u get caught they can arrest u so if u do it make sure u r close enough to the rails but far enough to run hahahha we did this when we were kids we would try & hit cars let them up cars go then down again then the railkroad police would come we were trouble makers kids & my friends didnot belive me this would work once they tryed it they went nuts blocking track hitting car they would make them go down for about 5 mintes on bussy road cars would be tired of waiting then they would undo the wire rails go up cars would pull up lookin for train think it was ok to go then they would set them down on them they would be on the track geting scared thinkin train was comming then let them go it was only a single lane train track so only one train could come threw at a time beware of two lane tracks a train may come & run ur azz over o ya dont try this on a electric train track u will get the shock of ur like if u touch the third rail like death ZAP fried toasted done so l dont recomend trying this but it does work

l also triggered crossings during halloween years back, but the railroad seem to have gotten smarter & changed the sensing to what l suspect a small computer device. Shorting the two tracks no longer brings the lights & gates down. With a little deductive reasoning l was about to take a pipe, fastened on a end of a broom handle & short the tracks about a 1/4 of a mile down & then run with it toward the crossing, keeping the tracks shorted. l suspect that the device is measuring the resistance change & speed of the train. Then l just left the rails shorted.
Great gag, but l am sure, real trouble can arise form being caught. For educational use only. Good luck with ur choices!

It called the OS circuit (operating system). The section of the track (Rails) at grade crossing is separated by insulated joints When the train cross these joints the wheel complete the circuit & the signals will come on. There is also a timer the will turn off the signal if the train stops within the circuit.
Lay any metal or wire between the two rail within the circuit will set them off, but the dispatch will send someone to investigate it he knows that no train is in the ares.

l have to say l wish u folks would not have answered this.At least not with how u were trying to trick the gates into activating.Now no telling how many kids r going to run out & try this never thinking they could end up dead or even worse cause a crossing accident because a car went around gates that r stuck down.People have a herd mentality sometimes & will blindly follow another car around gates without looking.A good way to get someone killed. l know u folks want to help answer questions but some r better left unanswered.And to all u thinking about going out & trying this ..THINK AGAIN,it is a federal offense that the consequences of could stick with u for the rest of ur life.Please stay away from the tracks.it is just not worth it!