Back when there was more passenger service I regularly saw short combinations of RDCs running in CTC territory. Apparently a single RDC at high speed might occasionally not knock down the circuit at a control point (CPR's North Toronto Sub) but CN seemed to have had no problem running two or three car sets on their Kingston Sub. That was with 1960s era signal technology.
The problem here is likely less the age of the signal plant or the characteristics of its relays than the effective electrical contact of the train across the rails. There are a number of factors that can surprisingly reduce this for lightweight equipment, including used traction sand, rail corrosion, and (I suspect) some forms of rail lube.
It my understanding that RDCs required special low-resistance bridging with brushes bearing on the 'clean' area of the wheel tread to provide consistent positive signal application. I'm a bit surprised that Amtrak can't provide something similar on its dedicated equipment in these corridors.
OvermodThe problem here is likely less the age of the signal plant or the characteristics of its relays than the effective electrical contact of the train across the rails. There are a number of factors that can surprisingly reduce this for lightweight equipment, including used traction sand, rail corrosion, and (I suspect) some forms of rail lube. It my understanding that RDCs required special low-resistance bridging with brushes bearing on the 'clean' area of the wheel tread to provide consistent positive signal application. I'm a bit surprised that Amtrak can't provide something similar on its dedicated equipment in these corridors.
The story I was handed by multiple B&O/CSX signal personnel has been that a single unit of equipment (RDC, single light engine etc.) can traverse the relay detected signal circuit faster than the relay can operate. Take it for what it is worth!
With CN & UP requireing 30 axles - they must not have a relay based signal system - they must be using a arthritic order of Monks with bad reaction times.
Never too old to have a happy childhood!
No, if we the citizens build a second main there or anywhere else, it is ours--that is for passenger service any hour, any day, the Class 1 can request and pay for access slots just as Amtrak or local passenger agencies have to on the existing tracks. See goose, gander.
BaltACDThe story I was handed by multiple B&O/CSX signal personnel has been that a single unit of equipment (RDC, single light engine etc.) can traverse the relay detected signal circuit faster than the relay can operate. Take it for what it is worth!
What this indicates to me is that a certain number of axles is necessary to assure enough current to move the relay, with its internal damping controlling how fast it moves -- with the active length (between insulated joints of the rail section) short enough that even though only, say, two axles' worth of contact provides enough current flow, you need up to 30 axles sequentially passing the insulated section at high speed, each two taking up from the previous ones as they pass, before the relay definitively socks in. That actually makes sense. You'd need some internal damping, as with vane relays, otherwise things like stray currents from moisture and salts in the ballast might be throwing them erratically...
BaltACD n012944 runnerdude48 Amtrak passenger trains (Other than the City of New Orleans) on the Canadian National ex-IC line operate with old Heritage Fleet baggage cars, diners, and sleepers in order to activate the signals. This seems to me to be kind of silly as no other short passenger trains tha I have ridden need to do this. I may be wrong on that as I have been in the past. The UP requires Amtrak to have 30 axles in both Missouri and lines north of LA. https://www.trainorders.com/discussion/read.php?4,4845926,page=3 Which, I personally, find as being a pile of bovine crap. So when UP has a light engine move over the territory they require themselves to have either 5 6-axle units or 8 4-axle units?
n012944 runnerdude48 Amtrak passenger trains (Other than the City of New Orleans) on the Canadian National ex-IC line operate with old Heritage Fleet baggage cars, diners, and sleepers in order to activate the signals. This seems to me to be kind of silly as no other short passenger trains tha I have ridden need to do this. I may be wrong on that as I have been in the past. The UP requires Amtrak to have 30 axles in both Missouri and lines north of LA. https://www.trainorders.com/discussion/read.php?4,4845926,page=3
runnerdude48 Amtrak passenger trains (Other than the City of New Orleans) on the Canadian National ex-IC line operate with old Heritage Fleet baggage cars, diners, and sleepers in order to activate the signals. This seems to me to be kind of silly as no other short passenger trains tha I have ridden need to do this. I may be wrong on that as I have been in the past.
Amtrak passenger trains (Other than the City of New Orleans) on the Canadian National ex-IC line operate with old Heritage Fleet baggage cars, diners, and sleepers in order to activate the signals. This seems to me to be kind of silly as no other short passenger trains tha I have ridden need to do this. I may be wrong on that as I have been in the past.
The UP requires Amtrak to have 30 axles in both Missouri and lines north of LA.
https://www.trainorders.com/discussion/read.php?4,4845926,page=3
Which, I personally, find as being a pile of bovine crap.
So when UP has a light engine move over the territory they require themselves to have either 5 6-axle units or 8 4-axle units?
Well, it COULD be that the grade Xing system the UP is using doesn't do very well at measuring the approaching train speed of small passenger trains. They do it by measuring the rate of change of resistance of the train approaching the Xing.
The LAST thing that you want to happen is for the Xing to activate late. Maybe that happens sometimes.
However, since these are routes with existing service, the host road should have signalling equipment that works with existing train sizes. The host RR requirement for added equipment over and above what Amtrak wants to operate should be fully paid for by the host road. This should include the extra fuel and extra wear and tear on the locomotive.
The passive agressive response would be for Amtrak to NOT add the extra equipment and stop and flag every crossing - which would put a hurt on the host road.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
oltmannd It's not "bovine crap". I personally know that UP had issues with passenger trains shunting for grade crossing signals on the Joliet-St. Louis line for a number of years (particularly in passing sidings), and they were actually running a non-revenue freight train back and forth on the line after hours to help address the issue (informally called the "Rustbuster"). I doubt that Amtrak has any problem with the 30 axle requirement if it's addressing a real issue. BaltACD n012944 runnerdude48 Amtrak passenger trains (Other than the City of New Orleans) on the Canadian National ex-IC line operate with old Heritage Fleet baggage cars, diners, and sleepers in order to activate the signals. This seems to me to be kind of silly as no other short passenger trains tha I have ridden need to do this. I may be wrong on that as I have been in the past. The UP requires Amtrak to have 30 axles in both Missouri and lines north of LA. https://www.trainorders.com/discussion/read.php?4,4845926,page=3 Which, I personally, find as being a pile of bovine crap. So when UP has a light engine move over the territory they require themselves to have either 5 6-axle units or 8 4-axle units? Well, it COULD be that the grade Xing system the UP is using doesn't do very well at measuring the approaching train speed of small passenger trains. They do it by measuring the rate of change of resistance of the train approaching the Xing. The LAST thing that you want to happen is for the Xing to activate late. Maybe that happens sometimes. However, since these are routes with existing service, the host road should have signalling equipment that works with existing train sizes. The host RR requirement for added equipment over and above what Amtrak wants to operate should be fully paid for by the host road. This should include the extra fuel and extra wear and tear on the locomotive. The passive agressive response would be for Amtrak to NOT add the extra equipment and stop and flag every crossing - which would put a hurt on the host road.
It's not "bovine crap". I personally know that UP had issues with passenger trains shunting for grade crossing signals on the Joliet-St. Louis line for a number of years (particularly in passing sidings), and they were actually running a non-revenue freight train back and forth on the line after hours to help address the issue (informally called the "Rustbuster"). I doubt that Amtrak has any problem with the 30 axle requirement if it's addressing a real issue.
So I am curious on grade crossings, why not place a RF tag on the lead locomotive and have the crossing signals do the math on the proxity of the tag to the crossing and trip the signals that way? Seems a lot less analog (vacuum tube) then the current system. I would think the computer capacity in locomotives today can figure out which is the lead locomotive in the direction of travel based on MU or whatever else they have as input......right? Lead locomotive activates the transmitter based on calc of lead locomotive and direction of travel which I would think takes nanoseconds.
Repeated radio geolocation between lead locomotive and grade crossing should be enough to determine when to trip the signals and how fast the train is moving. They allegedly have RF tags on all the freight cars these days so lets say it was just freight cars moving with no loco or it was a backup move. Get the crossing to recognize the frieght cars RF tags as well so it knows when the last car has cleared the crossing as well as it can tell when just rolling freight cars are approaching the crossing.
CMStPnPSo I am curious on grade crossings, why not place a RF tag on the lead locomotive and have the crossing signals do the math on the proxity of the tag to the crossing and trip the signals that way?
I believe it is the Canadian QNS&L that implements the anticollision function of PTC with radio transponders on locomotives. These get around some of the precision and location concerns with classical RFID by simply implementing a kind of geofencing: when two locomotives approach each other, the relative distance is tracked and alarms generated 'well in time' to preclude collision by surprise.
I've seen a number of proposals that use RFID as non-contact proximity detection for grade crossings. In most of these, the control would be improved if the "RFID" were in fact a true transponder capable of providing active information to the various wayside transceivers, instead of just a passive ID chip like E-Z-Pass which keeps its metadata in the associated network or cloud rather than in the device.
Thing is that most RFID tags are passive devices: they need to be energized by an external field in order to be recognized or to retransmit information. This is not an application where it would be 'safe' to use the kind of circuitry in theft tags, it must 'fail safe' at any time permission is not explicitly acknowledged, and this means a great many active electronic devices, with associated field security (and FCC IDs), failure of any of which would require an associated truck roll.
The infrastructure of PTC already provides most of the 'key' functionality to do variable crossing control, since it requires both a wireless communication to the locomotive and some fairly precise GPS tracking. With the addition of some fixed differential beacons it becomes relatively easy to 'program' interaction between the (secure) knowledge of locomotive consist speed and position and the variable actuation functions of a given crossing. (Note that for failsafe operation it is, in my opinion, unwise to rely entirely on this interaction for crossing operation: you still need a fallback 'minimum' circuit through the rails to detect things like rolling loose cars that won't self-report.)
Questions: What system does the UP use outside MO and the other areas in question? What do others use and why not adopt that nationally ? Why develop yet another complicated and unproven system?
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