How are railroad gates and lightes triggered to come on?

Question

Are they on a timer or is there a switch somewhere on the track that gets flipped when the train reaches a certin distance from the crossing. Or both?

Answer 1

Alrighty, first things first -- don't believe anyone who says trust me. (up above)

Secondly, its done by electrical circuit. There are low-voltage currents in the track, the wheels through the axle completes a circuit. The crossing voltage is contained to a block a certain distance from the crossing -- the track joints on each end of the block are insulated. Once the circuit is completed the crossings activate...

In industrial or heavy switching areas, there are some that have a delay circuit in the relay box.. The train has to move to a certain point and stop or slow down to activate the crossing...

There are some newer systems that there is a sensor in the relay box that can gauge the speed of the train and activate the crossing accordingly -- that is activating the crossing later for a slower train, or early for a faster train.

Its all rather simple... Block and other position signals work this way, and cab-signals work through currents in the rail picked up by an induction coil under the cab.

P.S. The "box with the antennae thingy" mentioned up above is absolutely not related -- that is a FRED -- or in other words, what replaced the CABOOSE... It monitors trainline brake pressure and has a Flashing red light for the Rear End. Also communicates with the headend telementry device so the engineer knows when brake pressure is equal within the whole train. It doesn't do anything related to crossings...

Answer 2

There are contacts on the track and when the train crosses them their metal wheels complete an electrical circuit.

Answer 3

On newer gates there is a laser (or speed sensor) beside the track, when a train goes through the laser its speed is calculated and this tells the gates when they need to go down according to the train's speed.

Answer 4

there is a sensor that is on the tracks that activates the lights and gates on the crossing the sensor also tells the speed of the train and can adjust times for the lights and gate  i work for the railroad so trust me

Answer 5

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Not true i always walk the tracks and the gates dont go down i think cory2107

needs his head checked

Answer 6

Blocks. When a train enters a specific section of track known as a block, the signals are triggered. The same concept is used to control train traffic and track trains. It is a very old technology but it works great.

Answer 7

they are wireless and get there signal from the train, look on the back of trains there is a box with an antenna that is part of the system

Answer 8

there is a motion sensor in the track, and when a train goes over it, the gates go either up or down.  either that, or it is wired with the signals, with a realy device connected to one of the rails.  when the train passes it, the realy device sends an electrical signal to the gates and they go down.