In the past, if a train was on a specific section of track near and over the crossing, the crossing lights and gate would be on. When approaching a crossing where trains do +60 mph, the section of track to trigger the lights are far down the tracks. Sometimes I see freight trains parked with the engine 10ft from the high speed crossing and lights off and gates up. One night I stopped to watch. After a few minutes, the horn blew, the lighhts came on, the train started on its way. Do the driver now have a remote switch to control lights now?
Posted by JONATHON (Member # 2899) on :
If you walk down the traxx, you can see where there wired for pressure
Posted by gp35 (Member # 3971) on :
quote:Originally posted by JONATHON: If you walk down the traxx, you can see where there wired for pressure
I thought it was the train completing the circuit between the 2 tracks. But that doesn't explain the train parking a few feet from the crossing with lights off.
Posted by irish1 (Member # 222) on :
i have seen train crews when they park close to a crossing walk up to the box and switch something within to shut it off. but by now they actually might have some type of remote on the newer units.
Posted by Mr. Toy (Member # 311) on :
I witnessed something similar a few years ago. An Amtrak train stopped to copy a track warrant maybe 1000 feet or so from a crossing. It tripped the signal and gates, but when it stopped the signal stopped flashing and the gates opened. A cautious minded truck driver stopped when he saw the train down the tracks, even though the gates were open. Once he realized the train was stopped, he proceeded across the tracks.
Anyway, the train was too far away for anyone to get off and control the signal & gates manually. So how it happened is still a mystery.
Posted by Geoff M (Member # 153) on :
I'm not an electrical engineer so my explanation may be slightly wrong. But in essence, the grade crossing prediction circuitry can detect how far away a train is and whether it's moving, a kind of electronic sonar. The wheels short circuit the two rails - there is normally a short track circuit over the crossing within the strike-in area, long enough for a train at maximum speed to give enough warning before the barriers come down. When a train strikes in, the speed is used to calculate how long it will be before it hits the crossing. At a fixed time interval before the crossing, the lights will start to flash and the barriers will go down. If the detection circuits notice that the train has stopped for a period of time, then the barriers will come up again. When it starts moving again, the barriers will come straight down.
Geoff M.
Posted by RRRICH (Member # 1418) on :
I believe the dispatcher can override the automatic signal system and operate the gates remotely if he is asked to do so from a train crew in a case like this, can't he?
Posted by George Harris (Member # 2077) on :
Crossing circuits:
Old style was a fixed length circuit with the length of circuit to give you the required minimum warning time at the maximum train speed. Therefore, they could blink for a LONG time with a slow train. Some were such that the lights kept blinking after the train passed until it got off the end of the circuit located for trains coming the other way. A particular nuisance with gates and really encouraged poeple to ignore the flashers and/or drive around them after the train had passed. (Actually quite safe on a single track line, but a really dumb move if double track.)
A step up from this was the use of "island circuits" which meant that you had to have another insulated joint close to the crossing on each side. This allowed the lights to quit and gates to go up shortly after the train had cleared the crossing.
Generally at all corssing there is a circuit control box. For most of these in areas where switching is likely to occur, there will be a start / stop switch located in a box which can be accessed by the train crew with their switch key.
Newer, actually for quite a few years now, circuits have a timing section of some sort so that the time the gates are down is near the same regardless of train speed. Even with the old style, a lot of the crossing controls had a timer in the control box that would stop the flashing and let the gates (if any) up after a set time, usually 5 to 10 minutes. The rules then required the train crew to either hand flag the crossing or push a start button, if there was one.
Posted by Geoff M (Member # 153) on :
Geoff M.
Posted by George Harris (Member # 2077) on :
Thank you for the link. Well worth the read by anyone interested, and despite being, as described, "more technical" not really difficult to understand.
Posted by Eric (Member # 674) on :
I watched a very, very slow moving freight train pass over a crossing several years ago, and the gates kept raising and lowering after each car passed, as the sensor kept "believing" the train was over.
Posted by gp35 (Member # 3971) on :
Today UP and the Poe-Poe was running a sting operation to get drivers going around crossing gates.
Posted by Kiernan (Member # 3828) on :
The grade crossing circuitry puts an audio frequency signal on the track and at a point down the tracks, a coil and capacitor in series shorts the tracks together. The location of the shunt depends on the maximum speed of the train. The circuitry then measures the impedence--just like the impedence of an old twin-lead TV lead in. If the impedence is decreasing, it means that the train is approaching. If the impedence is increasing, the train is moving away from the crossing. If the impedence is not changing, like when the train stops, the gates go up.
This has many advantages. If you several crossings near each other, you use a different audio frequency for each crossing, and that way the gates come down in sequence as the train moves along the tracks. With this system, the gates come up immediately after the train leaves the island section of the crossing. The island section is just a simple alternating current on the tracks that the train short circuits.
The systems are quite sophisticated, but I'm fairly certain that the circuitry doesn't actually measure the speed of the train.
Posted by travelplus (Member # 3679) on :
Actually the new gates will be computer controlled and it will read the GPS signal from the train and calulate the speed etc. As a safety measure if it detects a car or a person using a camera it will sound an alarm with a message"STOP TRAIN Crossing Gate#444 car or person on track" The system will send a signal to the train a couple of miles away. The gates might be linked to a computer where the engineer sees it on screen OK means he can go Error mans stop train something in the way. Manual means electricity out de-activate gate electric sysystem etc.
This will save lives. Each crossing gate will have a video cam so the engineer can see it miles away to stop the train .
Posted by Geoff M (Member # 153) on :
travelplus, that sounds like you're talking about the trials of the PTC high speed line in Illinois. It would certainly be too expensive and too high a cost-per-life-saved to be widespread on ordinary (sub 80mph) lines.
Are you sure about the video? A location with many crossings close together would mean a lot of simultaneous video streaming required.
Geoff M.
Posted by Big Merl (Member # 3251) on :
I heard UP is working on a new system where the gates will go across the tracks instead of the road. The gates will lower if they sense an Amtrak train is coming. It is part of their Total Delay by 2007 initiative.
Posted by George Harris (Member # 2077) on :
quote:Originally posted by travelplus: As a safety measure if it detects a car or a person using a camera it will sound an alarm with a message"STOP TRAIN Crossing Gate#444 car or person on track" The system will send a signal to the train a couple of miles away.
This sounds totally impractical. It is essentially a prescription to stop trains unnecessarily a lot of times. The current system is supposed to give a 25 second minimum gate down time (somebody correct me if that is wrong) which is plenty of time for traffic to clear but far less than the time needed for the train to come to a stop. Do we really want a system that will cause the crossing to activate some 3 to 5 minutes before the train arrives, because that is what this system will have to do to avoid sending the trains a message to stop.
Posted by Kiernan (Member # 3828) on :
You're right on the times, George. The highway traffic engineers want a time of 25 or 30 seconds, but the railroads always want it to be longer. The accident data indicate that if the time is much longer than 30 seconds, people start pulling around the gates. That's not to say that they don't pull around the gates, anyway.
I'm going to ride the RailRunner tomorrow morning. It's not the first day of revenue service because it's free, but it's the first day.
Posted by vdsteelman (Member # 4497) on :
What about MOW's??? I was train chasing one day and out of nowhere comes this MOW and no signals were set off. Can someone explain this?
Posted by vdsteelman (Member # 4497) on :
Also, how do EOT's work as far as knowing when the end of train has reached clear of a crossing? I was at a crossing one day and right after the train had cleared the crossing, it stopped to wait for another train. Is this because the engineer knows how long the train is and where to stop not to block a crossing, or is there technology in the EOT to tell them that they're clear. Any ideas?
Posted by George Harris (Member # 2077) on :
Because MOW vehicles are so light they are unreliable in shunting the circuit for signals, so they are deliberately insulated so that they will not shunt. Normally MOW vehicles are required to stop and flag or wait for road traffic to clear at road crossings.
Length of train is known to the engineer. This is necessary for the example you gave and also toe know where to stop in sidings and which siding you can or can not clear up in.
Posted by Eric (Member # 674) on :
quote:Originally posted by vdsteelman: Also, how do EOT's work as far as knowing when the end of train has reached clear of a crossing? I was at a crossing one day and right after the train had cleared the crossing, it stopped to wait for another train. Is this because the engineer knows how long the train is and where to stop not to block a crossing, or is there technology in the EOT to tell them that they're clear. Any ideas?
Before each tour of duty, the crew is given a manifest list and info about the train length and weight. Each locomotive is equipped with a computerized "foot counter," which the engineer can activate upon entering a siding, block, etc. The crew can then determine how far past a fixed point the train has traveled, and make sure that they are clear of crossings, main tracks, etc. I'm not sure if the EOT can also measure distance, although the counter might be tied into it somehow.
Posted by George Harris (Member # 2077) on :
Unfortunately, sometimes train length is like an arguement where there is my version, your version, and the truth. That is for length, what the engineer and conductor think it is, what the dispatcher thinks it is, and what it really is. As long as all numbers are close, no problem. As long as the real length is the shortest number, also no problem. When the real length is longer, then you can have a real oops if it exceeds the clearance length of the siding the dispatcher puts you in.