crossing gates

[MBTA F40PH-2C 1050]

how come the grade crossing gates aren't down? I am not 100% sure of how these work but is it because the train has been sitting too long and the circuit cut out? It doesn't look like there is any crew in teh cab

http://www.railpictures.net/viewphoto.php?id=74416[/i]

[TerryC]

The link should be http://www.railpictures.net/viewphoto.php?id=74416. The [/i] should not be there.

http://trainiaxindex.cjb.net/
keep asking keep learning

[MBTA F40PH-2C 1050]

oh, thanks, i didnt even notice that, i must have it by accident

[SRS125]

the circuit will cut out after a few minuets if movement of the train stops between the circuit and the crossing it all depends on how the railroad sets its crossing warning devices up. Its part of a defalt system. The same rule gos for a black out. If a black out were to happen some gates will drop and stay down till the power is restored.

[txbritt]

Crossing gates are set up with two sensors on each side. A couple hundred yards away from the crossing, and a couple right up on the crossing. The first set the train encounters trips the crossing arms, and they drop. If the locomotive stops between the sensors, the arms will time out, and the gates will raise. If the locomotive trips the second sensor, the arms will stay down until the last car has passed the closer sensor on the opposite side.

Most crossing arms that I've seen are battery powered with a constant charger from ground power.

Britt

[MBTA F40PH-2C 1050]

oh ok thanks guys

[Santa Fe Sucks]

Crossing gates are set up with two sensors on each side. A couple hundred yards away from the crossing, and a couple right up on the crossing. The first set the train encounters trips the crossing arms, and they drop. If the locomotive stops between the sensors, the arms will time out, and the gates will raise. If the locomotive trips the second sensor, the arms will stay down until the last car has passed the closer sensor on the opposite side.

Most crossing arms that I've seen are battery powered with a constant charger from ground power.

Britt

Where is that in use? We don't have them on my (BNSF) line, the only way crossing gates are activated is by shunting a circuit near the crossing.

[AmtrakFan]

BNSF is starting to get UP gates that ring for ever.

John

[SRS125]

CSX/NS and anything that was former Conrail property is set up with an A & B Senser that trips and shuts off when trains stop between them then drop again when movement trips the senser.

[Santa Fe Sucks]

CSX/NS and anything that was former Conrail property is set up with an A & B Senser that trips and shuts off when trains stop between them then drop again when movement trips the senser.

I have a hard time believing that, because 1.) I've never seen them, and 2.) without getting such sensors the gates timeout and go up anyway (negating the logic for the additional cost of sensors).

[trainmaster_1]

There are 2 systems that railways use, if its not one its the other, the first is a shunting system where if a train is nearing a railway crossing at grade the system sends out a electrical signal along the rail to see how far and how slow or fast the train is moving to set off the appropriate time to activate the crossing, the other such system is an oldie and is still being used today, and that is the use of insulated joints that keep the polarity poles and the electrical contacts different on each section of track for example, there are 2 sections of track, track A has the south rail negative and the north rail positive, when it comes to track B the polarity reverses so now the south rail is positive and the north rail is negative and this goes back and forth along the mainline. But anyways when a train passes over a insulated joint the relay's in the signal cabinet short out causing the crossing to activate due to that the train created a electrical connection on that insulated joint, when the end train has passed over the 2nd last insulated joint after the crossing, the relays in the signal cabinet reset and the crossing has stopped activating, but also the polarities changed when that train passed over that section of track too. Also if a train activates the crossing and stops inbetween the first set of joints they went over and the second that they didn't reach then the crossing stops activating and the gates go back up the max time for the delay is 20 seconds. But there are instances where if a train is stopped to close to the crossing due to that they made a lift at a siding somewhere and they had to block the crossing, the crossing stays active no matter what until the train has fully cleared the second set of insulated joints in order for the crossing to reset itself.

[SRS125]

I have seen this in action as well Tranmaster_1

With the gates droping and holding till the train clears. I think these gates also have the same defult where as if there is a power outage the gates drop and stay on till the power is restored. In my opinion this system dose not have as many poblums as the outher net work of sencers where the weather can play around with them causeing the gates to jump up and down.

The sencer system has been around sents the NYC according to a signal mantainer friend of mine who worked formerley for PC, CR, and is currentley with CSXT. The sencers on the rails I have seen this on many of the older Branch lines that Conrail sold off or leased to outher lines you won't see them on the main lines. They run on the system that Tranmaster_1 just explaned with the positive and negitve rail fult system. With a timeing device that sets the gates to drop according to train speed and distance from the crossing.

[trainmaster_1]

In my opinion this system dose not have as many poblums as the outher net work of sencers where the weather can play around with them causeing the gates to jump up and down.

I agree with you there, the weather does play around with the system and sometimes you may get false activation where the crossing activates for no apparent reason because of water getting into the relays, but also to add on top to what SRS125 said, faulty relay's could be to blame too, there was one past instance on the Canadian Pacific Railway where I was railfanning and whenever an eastbound train would clear the crossing and the tail end would be a 1/2 mile down the main the crossing would activate not only one, two times but three times and sometimes the gates don't go down completely but then the gates would go down completely when the relay failed so then they have to replace it. So there are sometimes more than 1 factor that railway crossings activate for no apparent reason when no train is around except for power outages.

[SRS125]

Just as an intresting side note the idea for a sencer type gate was thought up in the 1890's weather it was used by any railroads remains a question on my mined? But its kind of cool to think that someone was dreamed the idea up so long ago.

[Komachi]

In response to trainmaster_1's comment...

"I agree with you there, the weather does play around with the system and sometimes you may get false activation where the crossing activates for no apparent reason because of water getting into the relays...

I remember a number of times when the CP/SOO line crossing on Huff St. in Winona, MN would activate because of frost buildup on the relays during the winter. Lights were flashing, bells ringing and the gates would lower 1/4 of the way before going back up, quite a sight to see.