Fair enough. You seem to want railroading to grow and prosper, and I'll take your statement as a challenge that we need to do a better job communicating what we're doing. Most industries are quite complex and thus incomprehensible from the outside, and if the industry doesn't put much emphasis into communicating with the public it's an easy step from "incomprehensible" to "dumb." You should try railroading on the inside -- then you'll have a whole new appreciation for what we get right and what we get wrong!
S. Hadid
1435mm wrote: 20 years is a very long time, technologically speaking. So it should be easy for you to prove that. Go ahead. S. Hadid
20 years is a very long time, technologically speaking. So it should be easy for you to prove that. Go ahead.
1435mm wrote: GPS is used in CBTC (communications-based train-control) systems, which is an outgrowth of the BNSF Generation 1 ETMS (electronic-train management system), an outgrowth of the CSX CBTM (communications-based train-management system), which came from the Rockwell-Collins ARES system tested on BN about 15 years ago, which was the first system to employ GPS as a method of eliminating track circuits for train-location detection. (ARES worked very well, by the way.) Rockwell-Collins spun off their train-control effort to Wabco which later renamed itself Wabtec.
Brian (IA) http://blhanel.rrpicturearchives.net.
Datafever wrote:Well, I personally would not consider +/- 3 meters to be a big margin of error for a $200 unit (unmapped).The GPS satellite system no longer uses SA to throw a 30 meter margin of error into the signal. The military removed that years ago. It is now possible to purchase consumer products that can pinpoint an accurate location to under one meter, but that kind of accuracy comes as a big price.Nevertheless, I suspect that railroads will continue to lag current technology by twenty years or so. And there is nothing wrong with that.Have a good day, gentlemen.
jeaton wrote: Use of GPS to pinpoint the location of trains has sort of become the holy grail for some who think it must be part of the ultimate crash avoidance system. Knowing where a train is located is only a fairly small part of the process of getting trains moved over the railroad. Even if GPS could be used to identify the exact location and there were no signal loss problems, it is still providing no more information than that which is known by the train crew. The big part is moving the location information from the train to the dispatcher and the electronic support to his decision making process, then getting instructions back to the train crew and finally getting a feedback to the dispatcher indicating compliance with the instructions. There are many systems in place that accomplish the goal of keeping trains from running into each other, and those involving GPS are not necessarily the better mouse trap. It has been authoratively reported that the train control system designed for installation on the formerly dark Iraq Railroad had a cost of about 20% of "conventional" systems with lineside signals and it did not involve GPS. Cost and usefulness! You may notice that railroads have also taken a pass on another recent develpment and haven't put flat screen HDTV set in locomotive engine cabs.
Use of GPS to pinpoint the location of trains has sort of become the holy grail for some who think it must be part of the ultimate crash avoidance system. Knowing where a train is located is only a fairly small part of the process of getting trains moved over the railroad. Even if GPS could be used to identify the exact location and there were no signal loss problems, it is still providing no more information than that which is known by the train crew. The big part is moving the location information from the train to the dispatcher and the electronic support to his decision making process, then getting instructions back to the train crew and finally getting a feedback to the dispatcher indicating compliance with the instructions.
There are many systems in place that accomplish the goal of keeping trains from running into each other, and those involving GPS are not necessarily the better mouse trap. It has been authoratively reported that the train control system designed for installation on the formerly dark Iraq Railroad had a cost of about 20% of "conventional" systems with lineside signals and it did not involve GPS.
Cost and usefulness! You may notice that railroads have also taken a pass on another recent develpment and haven't put flat screen HDTV set in locomotive engine cabs.
I realize that train-control is an arcane science even inside railroading, and much of what has been distributed to the public is badly written if not incomprehensible, so please don't take offense if I point out that GPS is already in use on U.S. railroads for train-control applications and it does have value, if not silver-bullet value.
The problem with GPS is that it provides physical values whereas train-control requires logical values. This is an extremely important distinction that elides most observers of railroads. Because trains are constrained to tracks (a logical system) train-control requires logical inputs. GPS provides a physical input that says "you're sort of here, most of the time," whereas a train-control system says "you're either here or not here, all of the time." Because there's no way to measure physical location precisely or accurately, electronic train-control systems use logical either/or methods, such as track circuits (either open or shunted) or transponders or inductors (either passed or not passed). Manual train control systems such as train orders or TWC use manual logical inputs, e.g., "I am on the main track," or "I have left the main track." Yes, electronic circuits can fail but there are fail-safes built in plus redundant paths that makes shunted (occupied) the default condition and open (not occupied) the special condition. "Failure to shunt" resulting in a collision or injury is extremely rare.
The issue with GPS is that it's fuzzy, and while most of the time it will discriminate which track a train is on, and which side of a track cut (insulated joint) a train is on, it cannot do this reliably. (Do you want to get on an aircraft with a 1 in 10,000 chance of crashing or a 1 in 1,000,000 chance of crashing?)There are ways to get around this. A transponder tag on the track will tell the system which exit a train has taken from a control point. The system architecture knows there's a tag there and if the GPS indicates the train has run 150 feet past the tag location and the train hasn't not found it (because the tag has vanished, usually), the GPS can no longer "map" the train to a specific track, the system goes to a failed state, and the train is braked to a stop as well as any movements that may be opposing it. The way around determining which side of a track cut a train is on is to only care about one side of the track cut. You set one side as controlled track and the other side as uncontrolled track, and set a GPS fence where any train approaching the track cut is assumed to be continuing to the other side of the track cut, and predictively brake any train to restricted speed as it approaches the track cut heading toward uncontrolled territory, and predictively brake any train to a stop as it approaches the track cut heading for controlled territory. As is obvious these solutions to GPS fuzziness greatly reduce track capacity and train speeds, and neither will absolutely prevent collisions between trains that violate their authorities, just make them occur at low speeds.
GPS is used in CBTC (communications-based train-control) systems, which is an outgrowth of the BNSF Generation 1 ETMS (electronic-train management system), an outgrowth of the CSX CBTM (communications-based train-management system), which came from the Rockwell-Collins ARES system tested on BN about 15 years ago, which was the first system to employ GPS as a method of eliminating track circuits for train-location detection. (ARES worked very well, by the way.) Rockwell-Collins spun off their train-control effort to Wabco which later renamed itself Wabtec. ETMS uses differential GPS to determine train location, and RF interfaces with wayside signals, switch-point indicators, and electric locks to determine the condition of wayside devices. Peer-to-peer communication is used to reduce transmission and processor loads. ETMS is pending FRA approval only as an overlay system to traditional methods of operation such as CTC and TWC, not as a stand-alone method of operation. The ETMS overlay system provides an order-of-magnitude increase in safety by providing predictive braking of trains approaching authority limits and permanent or temporary speed restrictions. FRA approval of ETMS or CBTC as a method of operation hasn't even been asked for yet by any U.S. railroad. Federal law (49 CFR Part 236 Subpart H) requires a railroad proposing a new method of operation (e.g., CTC, DTC, TWC) to prove that the new method is as safe or more safe than the existing, plus propose in detail how the railroad intends to manage the implementation and maintenance of the system. That proof is both expensive and time-consuming; the railroads are not at fault for this. One could say the FRA is not very fast on this, but Congress and the White House have given them a law and a personnel incentive system that rewards ultraconservativism. But frankly, management of methods of operation is vastly more expensive and complicated then even most people in the railroad industry realize, and making changes in them is a high-risk, high-cost undertaking.
The Iraqi system, as I understand it, is a partial implementation of the BNSF ETMS system. It also uses GPS to map trains onto a GPS database of the track layout, plus transponders to identify control-point exits, but unlike ETMS it gives up all control of turnouts and sidings. That is, the Iraqi system only controls main track between stations (or main track between sidings, in U.S. practice). Stations are treated as non-controlled track operated only at restricted speed (yard limits, in other words) and trains are required by rule to brake to restricted speed before entering a station. The Iraqi CBTC system reactively brakes trains that do not reduce speed appropriately upon approach to a station (reactive instead of predictive because train consist and braking equipment condition is not known). But an improvement that ETMS doesn't have is that instead of merely displaying the authority to the train gr
tree68 wrote: While GPS may not be accurate enough for traffic control, it can certainly be used for all sorts of traffic monitoring - the DS can look at a display and know pretty much exactly where every train is - down to +/- 3 meters. Add a GPS to the EOT and you can now see where both ends of the train are. Combine the train location GPS info with the RFID info being discussed in the "bar code" thread and you know pretty much exactly where every car that's in transit is. Of course, there are some down sides - if the crew decides to stop for ice cream, the DS can see it. A comment in a TRAINS article mentioned a crew using a GPS to check their speed (something I've done, too). Well, the DS, TM, RFE, etc, can probably do the same thing, too. From their desk.
While GPS may not be accurate enough for traffic control, it can certainly be used for all sorts of traffic monitoring - the DS can look at a display and know pretty much exactly where every train is - down to +/- 3 meters. Add a GPS to the EOT and you can now see where both ends of the train are.
Combine the train location GPS info with the RFID info being discussed in the "bar code" thread and you know pretty much exactly where every car that's in transit is.
Of course, there are some down sides - if the crew decides to stop for ice cream, the DS can see it. A comment in a TRAINS article mentioned a crew using a GPS to check their speed (something I've done, too). Well, the DS, TM, RFE, etc, can probably do the same thing, too. From their desk.
This is a solution in search of a problem and misconstrues what dispatchers, trainmasters, and road foremen do with their time. None of them have the time or need to babysit trains. Knowing where the beginning and end of train might be is of no use. Either the train is in a block, or it's not. Fuzzy answers aren't suitable for train-control and is a flood of meaningless data otherwise.
As for speed enforcement, this is very convoluted. Better to do it onboard in real time with predictive braking curves. The point is not to fire crews, it's to keep trains from speeding.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
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Dave H. Painted side goes up. My website : wnbranch.com
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One thing left out of all of this…the GPS systems available to the public have a big, and I mean big plus or minus margin of error…
The Tom Tom and other “GPS” systems in your car really use a pre programmed map and a generalized location to function.
Unless you have a way to get the military to share their satellites and hardware, the error factor in the current GPS is pretty useless for train operations.
Now, if all you need is the general location of a locomotive, and an up link for service data, fuel, engine info, time standing, that sort of stuff, then it is already in use now…BNSF has it on most of their new locomotives.
So the only way to really utilize GPS in train control, in such a manner as it becoming a safety device, would be for the railroads to launch and maintain their own satellite and establish their own “private” system.
Datafever wrote: 1435mm wrote:1980s, actually, but it works reliably, so why change it? Railroading isn't driven by consumers who see more form than function, as are home electronics and autos.But even railroading must be able to gain advantages from advances in technology, such as GPS. I think that I would have gone crazy in the railroad world, knowing that there were much more technologically advanced ways to do things, but never being allowed to implement them because, "We've always done it this way, and it works just fine."Take that statement with a grain of salt please, as I am well aware that railroads do implement technological advances. They just do it at a slow, reasoned pace.
1435mm wrote:1980s, actually, but it works reliably, so why change it? Railroading isn't driven by consumers who see more form than function, as are home electronics and autos.
23 17 46 11
There are also huge benefits to standardization, even though the device may not have the latest bells and whistles. A RR might own thousands of these things, and has to maintain them either with their own forces or by using a contract shop. When you are talking hundreds of parts per item, the cost of inventorying spare parts can go astronomical quickly when you start adding different models. That doesn't count the costs and frustrations of having qualified repair staff available, who have to be trained on each different model they maintain.
Datafever wrote: 1435mm wrote:1980s, actually, but it works reliably, so why change it? Railroading isn't driven by consumers who see more form than function, as are home electronics and autos. But even railroading must be able to gain advantages from advances in technology, such as GPS. I think that I would have gone crazy in the railroad world, knowing that there were much more technologically advanced ways to do things, but never being allowed to implement them because, "We've always done it this way, and it works just fine." Take that statement with a grain of salt please, as I am well aware that railroads do implement technological advances. They just do it at a slow, reasoned pace.
Datafever wrote:I notice that the device does more than just measure distance from a setpoint. It is also a communication device with a transponder ID. What it is communicating with - the EOT? If so, is the displayed pressure reading from the EOT? BTW, I understand rough and rugged. My comment about it looking old did not stem from its beat-up appearance, but from the antiquity of the visible components such as the LCDs and the overall user interface. Looks like something right out of 1970. Thank you, both Ed and Mr. Hadid, for your replies.
Data,
Mr. Hadid is quite correct, in fact, that one is pretty “clean” looking.
Usually they get pretty beat up and banged around.
Having it rugged and over engineered are the keys to equipment surviving use on a railroad.
You should see the cab radios, or the hand held ones we carry, old Motorola JT1000s and such, clunky and plain, but they survive being dropped, kicked, getting wet, and being treated pretty rough.
On some units, the calibration setting is done by the shop crews when they pull a locomotive in for its 92 day FRA look over, they measure the wheel diameter and reset the rev counter based on the wheel wear, in other words, one axel revolution equals X number of feet traveled, which is why, unlike cab radios, you rarely see these units swapped out from locomotive to locomotive.
If it is not noted on the device that such a setting has been done, then as Mr. Hadid pointed out, the engineer can set it using a measured mile when you depart.
Willy2 wrote: CShaveRR wrote: Yes, Sis (and others), speed limits are very closely enforced. Sometimes the Weed Weasels have radar guns, and there is no tolerance in the posted or timetable speeds. 79 m.p.h. maximum does not mean 80! As for the trackulence in the photo, I suspect that this sign, being as close to Camp Mookie and the diamonds as it is, probably indicates an increase in speed from what was in effect in advance of the sign, so one really doesn't have to worry about taking that particular stretch at 75 (no excuse, just an observation). What is the purpose of having 79 mph speed limits? Why don't they just call it 80 mph and be done with it? 79 mph is kind of like when advertisers say that something is $19.99. It had just as well be priced at $20.00.
CShaveRR wrote: Yes, Sis (and others), speed limits are very closely enforced. Sometimes the Weed Weasels have radar guns, and there is no tolerance in the posted or timetable speeds. 79 m.p.h. maximum does not mean 80! As for the trackulence in the photo, I suspect that this sign, being as close to Camp Mookie and the diamonds as it is, probably indicates an increase in speed from what was in effect in advance of the sign, so one really doesn't have to worry about taking that particular stretch at 75 (no excuse, just an observation).
Yes, Sis (and others), speed limits are very closely enforced. Sometimes the Weed Weasels have radar guns, and there is no tolerance in the posted or timetable speeds. 79 m.p.h. maximum does not mean 80!
As for the trackulence in the photo, I suspect that this sign, being as close to Camp Mookie and the diamonds as it is, probably indicates an increase in speed from what was in effect in advance of the sign, so one really doesn't have to worry about taking that particular stretch at 75 (no excuse, just an observation).
What is the purpose of having 79 mph speed limits? Why don't they just call it 80 mph and be done with it? 79 mph is kind of like when advertisers say that something is $19.99. It had just as well be priced at $20.00.
Datafever wrote:Thanks for the picture. That device looks old. Do you know anything about the technology that it uses to calculate distance? Does it just measure axle rotation as cars do? Or is there telemetry involved? Is GPS used at all?
Datafever, here is an example of the head end device with the counter in the top left corner.
CShaveRR wrote: Datafever, the engineer has a counter by which he can measure distance from a certain point when necessary. He (or the conductor in the cab with him) knows the train length.
Datafever, the engineer has a counter by which he can measure distance from a certain point when necessary. He (or the conductor in the cab with him) knows the train length.
Of course, a good engineer will know his locations and be able to calculate distance and time. If his train is 125 cars long, and the speed restriction ends at, say, milepost 55, the engineer should know that at milepost 56.25 his speed may be increased. He shoudn't need some darn gadget to replace his thinking ability.
In addition, if an engineer needs a counter to know where the rear of his train is, how could he possibly be able to figure out what speed he needs to travel (to avoid stopping and blocking crossings) when the dispatcher tells him that at the junction 14 miles ahead he will have to wait for a train that is 22 miles from said junction, coming in the opposite direction at 38 mph.
Willy, I agree with you--but in order for a line to be allowed to have an 80-or-over speed limit, it must have some form of advanced train control, such as Automatic Train stop, Automatic Train control, or other such.
Carl
Railroader Emeritus (practiced railroading for 46 years--and in 2010 I finally got it right!)
CAACSCOCOM--I don't want to behave improperly, so I just won't behave at all. (SM)
CShaveRR wrote:Normally the entire train has to go through the restricted area before speed may be increased.
Willy
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