What triggers the crossarm warning signs come down at Railroad crossings?

Question

Is it a certain point on the track or controlled from the locomotive itself?

Back when I was a young, stupid little hoodlum, we'd always try to get them to come down. We'd heard to put something heavy on the tracks or jump on them, put a wire across, etc.

I know it's totally random but it's one of those burning questions I've always had.

Answer 1

a track switch does the work from one rail to another a distance aways by contacof the wheels being metal

Answer 2

The trigger is a "bug".  They are activated by track occupancy and, in many insurances, movement.  In addition, many have time-outs on them so if the train isn't moving, the gates will raise.  In these instances, when the train is ready to proceed, the gates are reactivated either by movement, proximity (another bug, closer to the crossing needing to be occupied), sound (locomotive whistle), or, in some instances, a manual start requiring a key be inserted by ground personnel.  If all else fails, the train can enter and cross under flag protection by a flagman.

Answer 3

Usually there is a switch triggered up the track from the crossing. Since trains have been known to use both sides of the road in both directions for passes and such, you can assume the trigger mechanism is on all arms that extend out from the crossing, east and west on each of a double tracked alkignment, for instance.

Sometimes it has been a mechanical switch, other times Ive seen it triggered with photocell.

Fundamental answer, I realize, but hope it helps. I have MANY burning questions myself, so dont feel bad.

Answer 4

when you were a young hoodlum you never walked far enough away from the intersection of the  tracks to the road crossing   --- the speed of the train and the weight of the locomotive and the distance to the X'ing are all factors to the bars being lowered to stop the traffic  ....

Answer 5

I used to plow snow with a bucket loader and once I had to take it on the tracks to remove a heavy drift, Got a fair ways out there and noticed the arms were going down... scared the...heck out of me. I'm still not sure what triggured it, either weight or the metal bucket touching both tracks.

Answer 6

HOGHEAD nailed it again...but I would like to add...never trust crossing warning lights...they tend to fail in bad weather...always look both ways...ALWAYS