RR Crossing Gates

[Grandma B]

While watching several Amtrak Silver Meteor videos on You Tube, I noticed on some of the down south country RR crossings, that the gates appeared to lower just prior to the trains approach. With the trains traveling at top speeds, is there a rule/law as to how much time/distance before the gates are lowered for an approaching train?? I guess, I'm use to sitting at LIRR gates that are down for a length of time before a train approaches.

 

[Shawn]

It's roughly 25 seconds from activation of the signals till the train enters the crossing. The gates usually have about a 5 second delay and take roughly 10 seconds to lower (+/-). So, roughly 10 seconds prior to the train entering the roadway, the gates should be lowered. Of course, most gate systems are computer controlled now..and can vary slightly...

 

[battalion51]

The timing depends on the crossing. Some crossings (in urban areas) may have longer lead times than in rural areas. If the crossing is protected the gates should be on the ground by the time the motor hits the crossing.

 

[wayman]

It's roughly 25 seconds from activation of the signals till the train enters the crossing. The gates usually have about a 5 second delay and take roughly 10 seconds to lower (+/-). So, roughly 10 seconds prior to the train entering the roadway, the gates should be lowered. Of course, most gate systems are computer controlled now..and can vary slightly...

But how does the automation which triggers the gates work? If it's by a physical sensor in the track (the train completing a circuit at a specific point or providing weight at a specific point), then all we can measure precisely is the distance of that point from the grade crossing. The time from when the train reaches that trigger point to when it reaches the grade crossing is variable: it depends on how fast the train is going. If the grade crossing trigger is timed to give 10 seconds of "gates are completely down" for a freight train (going, say, 40mph), they'll give a lot less time for the occasional passenger train (going, say, 60mph).

In the Philadelphia suburbs, gates are fully down for perhaps fifteen seconds before SEPTA commuter trains enter the grade crossing. It's always been my observation that many motorists view "the lights are flashing and the bell is clanging, but the gates aren't down yet" in much the same way as they view "a yellow traffic light"--they think "oh, I should speed up!". They shouldn't--but they do. Even those impatient motorists view gates that are down as "I must stop". I'd feel better about gates going down about ten seconds earlier than they actually do in most situations.

 

[Grandma B]

Thank you all for your answers. Between hearing the horns blasting and observing the flashing gates down at the crossings, I just pray that nobody tries to beat the train. Seems like a very short amount of time for a train traveling at top speeds. :blink:

 

[Shawn]

Most crossing systems now are computers. They "sense" the train and then calculate the speed of the train and predict how long it will take the train at it's average speed to reach the crossing. It then takes all these calculations and trips the lights/gates at the 30 second time. It is also able to sense if a train has stopping within the circuit and will raise the gates. Of course, it also knows if the train is within a certain distance from the crossing or has occupied the crossing and in that case, it will not allow the gates to raise.

Ok, yes, all very complex. Welcome to the computer age.

 

[battalion51]

The gates use the electrical circuitry in the tracks. There's a very low voltage thats sent through each rail, when an axle is on the rail it completes this circuit. The computer at each crossing detects the train, estimates when it will arrive at the crossing based on the speed its traveling, and lowers the gates accordingly.

 

[MattW]

That's why the NARCOA requires the wheels on raicars participating in their various trips be insulated from each other so they can't complete the track circuit. For NARCOA trips, cars have the right of way!

 

[ourlouisiana]

Don't have our paperwork in the house right now, but we think we understand the FRA ruling is the active warning device (bells, lights, gates) be activated not less than 20 seconds prior to the FASTEST train that passes through the crossing.

Computers and track sensors take care of the rest of the mechanics.

We have many videos of Amtrak #1 and #2 passing through south Louisiana, and the average time from activation to passage of the total train, 2 engines, baggage car and 6 Superliners is 50 seconds.