Everybody is well aware of Union Pacific’s problems now in Southern California and elsewhere – too much business, not enough infrastructure to run as many trains as they need to run.
I know that GPS signal control is being investigated – on the Alaska Railroad, among others.
So here’s my question – GPS train control will allow trains to operate much closer together. Obviously, if you are in a train and another train is on your track say five miles ahead it’s probably not a problem if its moving away from you at 60 mph. It’s a real problem if its stopped, or even worse, headed towards you at 60 mph.
If you could wave a magic wand and have total GPS train control over a system – how much would that increase railroad capacity?
What you are really talking about is Postive Train Control, which may use GPS as a component, or may not. It depends on the system. The capacity increasing aspect of PTC is it incorporates a system of “floating blocks,” that is, the blocks travel with the trains rather than are permanently fixed to geographic locations.
The short answer to your question is PTC might increase capacity, but at a cost that is very unattractive, so far. The electronic equipment is more expensive than traditional Centralized Traffic Control, which itself costs about $1 million per mile, because it requires equipping every locomotive and mobile track machine assigned to the PTC-equipped territory. The software is very complex and expensive – think fly-by-wire systems on an aircraft. If a railroad doesn’t equip its entire fleet with PTC, it takes upon itself a severe loss of flexibility in fleet management.
The fundamental difference between GPS and railroad methods of operation is that GPS is an approximation (albeit a pretty good one) and railroad operation is yes/no. That is, a train is either approaching a control point, or it has passed a control point. All GPS does is tell you where a GPS transceiver is – more or less – which is not at all the same thing as a signaling system. If an aircraft is plus or minus 20 feet while flying, who cares? A train plus or minus 20 feet is on another track or beyond a control point.
I’ve seen some bold claims of capacity increases with PTC, but there are many skeptics who disbelieve them. No one is rushing to buy it except people using other people’s money (that is, taxpayers’ money). We might see PTC experiments on high-density freight railroad routes within 10 years.
You asked how much capacity could be increased: no one knows the answer to that question yet. Manufacturers claim 20-30%, but no empirical tests to validate those claims have been performed. And without a huge committment of cash on someone’s part, a real-world i
Meter grade GPS is still insufficient for trains passing in sidings. This bug has been known since Rockwell’s LARS, NTRAC & ANSAC days in the mid- 1980’s… To get things down to survey grade RTK GPS you need beaucoup base stations and a ton of software to sort stuff out on the fly. (Thus the expense…plus if the receiver loses “lock” under a bridge, tree or building you’re had…then there is “multipath”…)
The little Garmin handheld GPS units are anywhere from +/- 15 feet to hundreds of feet off in precision (Precision & accuracy are NOT the same thing…and accuracy is subjective)…when trains can pass each other with 1 or 2 feet two spare, the uncertainty is too much…
In time the computer processing and hardware costs will drop, in the meantime we’ll just have to wait…Everybody is complaining about RCO’s, this makes RCO’s look like a minor bump in the road…
Travelin’ Feathers
ps…(GPS & GIS are not the same either, far too many do not understand the difference… Technology is a good thing - Failure to understand the technology creates unwanted expectations and/or blunders, as in brain failures that kill…)
Europe is going to announce that their new Gallaleo system will be compatable with GPS. They also won’t degrade the M code like the US does. Having more satellites and frequencies to read should help lessen lost or reflected signal problems.
As for having to equip every piece of equipment, why not just equip locos and ETs to pinpoint each end of a train?
I agree that GPS needs to be a component, not the whole shebang. Putting a GPS in both the FRED and the lead loco helps demonstrate train length. Adding some unit ID (such as the trucking industry now uses) with that helps the dispatcher keep track of who is where and how they are doing (all engines in notch 8, trainline normal, etc). On a straight section of track with no diversions, GPS with unit ID, together with some computer oversight (and a reasonable degree of confidence in the system), it would be possible to stuff quite a few trains in. Speed, weight, track profile, and the corresponding stopping distance could all be computed continuously, allowing train seperation to be minimal (factor in a cushion, there). Cab indications would replace lineside signals, and could give distance to next train, as well as a recommended speed.
On the other hand, for close quarters (yards, passing sidings) where exact location is crucial, there’s nothing like a track circuit.
But, all that tech stuff costs money. It’ll be a while.
As an example of the application, though, the Phoenix, AZ, Fire Department has equipped all their apparatus with a system that includes GPS. They now dispatch by the equipment closest to the scene, as depicted on a map of the city that shows where all apparatus are.
Larry: Interesting comparison you make to emergency services. It allows me to illustrate the difficulty of railroad operation. My wife was a paramedic and later a paramedic dispatcher for the city of Fort Worth. They dispatched using GPS and an electronic map of the city, just like you see in Phoenix. She thought railroad dispatching would be about the same, right? Wrong.
In her words, “railroad operation is more than 100 times harder than ambulance and fire apparatus dispatching.” Part of the problem is that railroads have one degree of freedom (forward and reverse) and used a fixed guideway, whereas rubber-tired apparatus have two degrees of freedom and a self-steering guideway. Thus, railroad operation is all on absolutes, all of the time. A train absolutely owns a section of track, and has absolute boundaries. GPS has fuzzy boundaries.
Regarding using GPS to measure train length, that only works on tangent track. GPS measures the position horizontally between two points and on a railroad those two points can vary significantly in the distance between them.
Consider a train approaching a loop track, the train is exactly as long as the loop is around. As it goes around the loop it gradually becomes “shorter” because the relative distance between the engine and EOT decrease until the Engine passes over the rear of the train and the length of the train effectively drops to zero. While this is an extreme example, the same distotion will occur on any curve, only to a lesser degree.
Mark and Dave - I agree fully. That’s why GPS has to be a part of the solution, not the whole thing. Even though GPS may be fuzzy, it still has a certain level of accuracy. Using the concept of factoring in speed, geography, train length and weight, and necessary buffers (to account for the fuzzy GPS), optimal distance could be maintained. For instance, if for some reason track speed was reduced, trains would be able to follow more closely, rather than be constrained by the fixed signalling system.
By mixing GIS (computer mapping), track circuits, and GPS, it should be possible to manage things very nicely. The fact that a railroad is a fixed plant can be used to advantage, as there is near absolute (never say never) control over what occupies the space. Very few alleys or side streets to worry about.
Re: Curves and Loops - Even an inexpensive GPS will mark waypoints. There is no reason why a railroad GPS tracking system should be any different. Thus with GIS and plotted waypoints, a computer system could track the length of a train very accurately, even with the fuzzy GPS finagle factor figured in. As for loops, while the “as the crow flies” distance between the lead loco and the EOT may be measurable in single digit yards, the tracking would take the loop into account and present a fairly accurate number. Combining that with track circuits and other sensors would reinforce the information.
I’m certainly not saying this is the be all and end all technology for controlling trains, but it’s probably going to happen some day. The technology exists today to make it happen. It still comes back to bucks. As already mentioned, all components must be suitably equipped, and the computers must be properly programmed to process the information and provide it to those who need it. When you add run-throughs, etc, it gets more complicated - witness the gyrations necessary with existing railroads that have special signalling systems.
Interesting concepts. I’m not a railroad man, although I’m a private pilot, and of course love the GPS systems.
A few thoughts;
First, I don’t think the GPS would need to be accurate enough to differentiate between parallel tracks. This information could be achieved by other means and transmitted back to the central computer the same way the GPS coordinates are transmitted. One thing that comes to mind would be a simple low frequency tone that is transmitted through the rails, different for each set of tracks. It would be simple for a computer to keep them straight. Even aircraft don’t rely solely on GPS units; a plane’s altitimeter gives a much more accurate report on a plane’s altitude than a GPS unit could ever hope to give.
Second, you would think the train crew would know which siding they are supposed to be taking. If they wind up on the wrong one they can certainly get on the horn and check out what’s going on with central command.
Third, you really don’t have to GPS determination of the length of the train. You already have that information when the train leaves the switching yard. For calculation purposes the train will always be equal to the calculated length from the number and type of cars plus a 2-3% fudge factor.
Fourth – As far as the GPS losing a signal? Not a problem. The central computer will know not to expect a signal from a train while it’s in Moffat tunnel, for instance. It can easily be programmed so that ten or twenty second interruptions are ignored. Anything longer than that will trigger a call to the crew – sort of a “Train 54, where are you?”
Fifth, as far as equipping every piece of equipment with a GPS and transmitter – Why? Wouldn’t it make more sense to regard the GPS sort of like a EOT device? In other words, the GPS goes with the crew and the unit is mounted in the locomotive they are using. It certainly can be made small enough to do this without difficulty.
First, one of the goals of PTC is to be able to extend signal-type protection to non-signaled track. If you have to install a signal system (circuits in the track) then you eliminate part of the benefit.
Second, the crew doesn’t know when they will be taking a siding or necessarily why. That is controlled by the dispatcher.
Third, the train length is provided by the lists and is fairly accurate, depending on wether the train has picked up or set out cars enroute.
Fourth, yes but what happens to the trains behind the train when it loses contact? If the train ahead disappears does the system let the following train speed up? If an opposing train disappears, does the system let the train in the siding out on the main?
You have to account for loss of contact because it will happen.
Fifth, yes but you would have to install it in every engine and every EOT, and it would have to be interactive, transmitting a location as well as recieving it. That’s a couple hundred thousand things to keep track of. Throw in on track vehicles and maintenance equipment, there’s another hundred thousand things to track. That’s a lot of satellite air time.
Sixth, that info is nice to know, but really the only thing they need to know is what signal indication or speed they need to move on or how long they will be stopped (to cut crossings, etc).
Seventh, you would probably need CTC to remain in effect at all times as a back up. Remember your first point, those signals in the track? Well that is a more complicated CTC system, so you can say you are “retiring” it but in reality you aren’t, you still have all and more of the cost with your coded signals in the track.
Finally because a little map isn’t interactive. You don’t have to be two way with a handheld mapper, you don’t have to have it stand up in -50 deg with a 90 mph wind and 2 ft of snow and then 120 deg heat a month later. Your littel GPS indicator doesn’t have to be 99.99999% reliable. Why do you think you can buy a a
The initial question I asked was how much the PTC/GPS system would increase railroad capacity by allowing more trains to be run closer together. I doubt (although I may be wrong) if there are any busy mainlines anywhere that are dark.
Now as to some of the points. . .
As it now stands the crew doesn’t know whether they are taking a siding or not. I don’t see the problem with a dispatcher telling the train crew which siding they should take and then having them confirm that they have done so.
What happens when trains lose contact? There two parts to this question. If GPS contact is loss, the computer will still have a very good idea where the train is from the history of its position and speed. If the GPS signal doesn’t return within x number of seconds, then radio contact will be made with the crew, and information about the train location and speed can be forwarded over the radio. If radio contact is lost, than the train will go into an automatic shut down mode – depending where the known other traffic in the system is. If the train is on a dark section of track with no other trains around for 100 miles it wouldn’t be quite as urgent to shut things down, as opposed to a busy mainline, where you would probably have CTC backup.
Every piece of equipment would not need a GPS transponder. Every individual operating a piece of equipment on the track would need one. Therefore, the GPS/transponder units would be portable, and go with a crew – the same way an EOT device is.
I might mention that air traffic control is done by the use of transponders. This is a piece of equipment located on almost every aircraft that continuinously transmits its identity and altitude to air traffic control. Before a aircraft takes off it is assigned a transponder code, which the pilot programs into the transponder. Central control takes that information and combines it with the radar sweep so that they see your
Returning to your original question, “how much could GPS increase railroad capacity?”
Answer: zero. It’s not cost-effective. It’s cheaper to buy more track. Railroads have asked that question already, and come to that answer already. Certainly, there are people in railroads who are old-fashioned and stubborn, but there are many that aren’t. The problem is that the technology is inappropriate to the application.
Not that railroads haven’t tried. GE Harris-Harmon, Lockheed-Martin, US&S, Alstom, Ansaldo-GRS, and Class I railroads have invested over $100 million to date in various types of radio-based train control. None have been found feasible on a cost-benefit analysis, and severe technical difficulties have been resolved only at tremendous cost. Some technical problems have proven resistant to solutions. There are several prototype sections in tests now in the U.S. (Amtrak Michigan Central; Illinois high-speed corridor, NJT). Each step has required expensive modifications, a lot of software debugging, and none of these systems is considered truly operational yet, at least in a form that holds any hope of increasing capacity. An automatic train stop feature, yes. But that’s all.
One month ago, I listened to a Lockheed-Martin presentation at the Kellogg School of Business at Northwestern University on the safety improvment value of PTC. Answer: zero. Train collisions and derailments caused by authority violations and speed violations that a PTC system could prevent are so rare that L-M had to multipy the data tenfold in order to subject it to standard methods of statistical analysis. Statistically speaking, wrecks associated with signal systems are indistinguishable from wrecks caused by random chance. After the meeting, the L-M engineer told me “I don’t know why anyone is bothering with this. I’m happy to take their money to do useless studies, but the truth is, signaling-caused wrecks are the least of the industry’s worries.”
It’s always so nice to read your stuff, Mark! I’d just like to doubly emphasize one point you made – everything – repeat EVERYTHING – we do out there is intended to be fail-safe. Which, in our context, means if something doesn’t check out, you stop. Can’t read the signal? Stop and find out what’s up. Signal dark? Ditto. Obscure alarm on the third unit back? Stop and find out what it is. Trackside detector sounds off? Time for a walk to find out. Aircraft don’t do that (they can’t!) – as a fun way to relax, I’m also a 6,000 hour plus pilot and proud owner of a Piper Arrow and I know…
And as you also pointed out, it’s a lot easier and cheaper to run the railroad the way we do now; signals and control aren’t the problem – track is.
Thanks so much for your reply. I had no idea that trains could operate at speed as close as three miles apart. That would pretty much negate any advantage for GPS to increase capacity that much.
I don’t have the current issue of Trains magazine with me. In the magazine you did mention the additional number of train crews and locomotives that were needed by Union Pacific as the average train speed decreased. From what you are saying I gather that the real capacity problem presently is at the terminals – not enough crews/locomotives/tracks available to break down and put together the trains that are arriving and departing.
I might tell you a little bit of my background. I’m actually a surgeon with a degree in electrical engineering, besides being a pilot. About the only thing I don’t really have any experience in is railroads!! Maybe that’s why they interest me the way they do.
I would suggest that you take your last reply and put it somewhere in one of the Trains issues. I think its an excellent analysis of the problem.
Well, you can’t read it YET because that’s the issue that’s in the mail! Sorry about that.
You know how it is from your profession: a little knowledge is a dangerous thing. Surely you get people saying to you, “I don’t understand why …” and you feel like screaming to them, “Do four years of medical school and a six year residency, and THEN maybe you’ll know!” I can say this because I did two and a half years of medical school before I realized that railroads really were where my heart was, plus the cost-salary ratio was widening exponentially before my eyes. Oh, and, I’ve had enough stick time in a 150 to land it, but haven’t completed my license in that, either. (Another issue of time and focus). I do read all the airplane magazines voraciously, though!
The real problem with railroads always has been the terminals. Just like airports. Over-the-road speed is useless if everything is just going to park at the other end.
Actually, there have been several significant developments in medicine from those outside of medicine.
The first that comes to mind is the Starr-Edwards heart valve, the first artificial heart valve that was really useful, and that was in the 1950s. He was developed by Albert Starr and John Edwards. It’s also known as the “Cage-Ball” valve.
Starr was a cardiac surgeon. Of course, in the 1950s cardiac surgeons didn’t do anywhere near as much stuff as they do now. John Edwards was an engineer who had invented an “artificial heart”.
He took it to Albert Starr, who thought the heart itself was pretty much useless, but that the heart valves it used were a terrific idea. Thus the birth of the “Starr-Edwards” valve. I had the pleasure of taking of doing surgery with Dr. Starr for several months when I was a resident.
More recently, some engineers outside of the field of medicine have been instrumental in the development of a cellulose compound that promotes clotting in surgical bleeding and various implantable objects.
Mark-Thanks for the view from the inside. It kind of sounds like a solution in search of a problem.
This is a little off the thread, but I’ve had an idea (dangerous, maybe) about block signaling. Without changing the basic logic and operation of block signaling, has anyone evaluated the concept of putting transponders in place of the typical wayside visual signals. Kind of like the Automatic Train Stop territories previously installed on the IC, MILW, RF&P, and maybe others but up dated. My concept has the paging receiving module portable so the need to equip every locomotive unit is avoided. This is not for replacement of existing block signal territory, but rather for new allignments, upgrading from dark territory, and, if such conditions exist, reducing block length to the two to three mile length to upgrade a low traffic line to handle more traffic.
Add an automatic train stop feature (with the override switch located so the engineman has to get out of his seat to activate it), and you meet the longstanding goal of NTSB to have this safety feature, and (correct me if I am wrong), you have a signaling system allowing 99 MPH passenger trains.
There is no doubt in my mind that a transponder on a post is far cheaper than a mast and lights. The cost question is the pager/reciever in the cab. If the numbers are right, maybe the system can be added to existing mainline block signaling and get the 99 MPH speed cheap.
There’s two parts to your question – method of operation and multiple main track.
First, method of operation. What you’re describing railroads already have: it’s TWC and DTC. Problems:
TWC and DTC do not have track circuits unless equipped with Automatic Block Signals, so there’s not much savings there. No track circuits, no broken rail or open-switch protection.
CTC gives you remote-control switches; without them, the train has to stop to line itself into a siding. That’s 20 minutes lost each time. Worse, the switch stays lined behind you, because you have no caboose, so the next train has to stop to make it “normal” for the main track. It gets a 20-minute hit, too.
No signaling means no protection from broken rails or open switches, so the FRA restricts you to 49 mph for freight instead of the 79 mph you can get in CTC.
No signaling means no protection from following trains (flagmen are SO gone), so trains can’t follow closely like they can with signaling.
Dispatcher workloads very quickly become intense, so territories become smaller. Basically, a CTC dispatcher can handle three times the trains as a DTC dispatcher. It was much less work to dispatch 35 trains at once between Kansas City and De Queen, Arkansas, with CTC, than 10 trains at once between Vicksburg, Miss., and Shreveport, La., which is about one-third the distance.
In short, CTC allows you to run 80 trains a day on single-track. BNSF does it! TWC and DTC max out at about 35 trains a day, and those trains are running at much slower speeds with less safety.
Now, multiple track. CTC is very expensive to install, but once installed it’s essentially zero maintenance, because code lines are no longer used (the code travels in the rail). Track, on the other hand, is fantastically expensive to maintain. 75% of the railroad revenue dollar goes to track maintenance. Track requires maintenance eve
One quick question, in order to throw a wrench into the works, how many tr5ains pile into each other due to the derailment of the lead train? Also, figure the costs of those delays. The concept sounds good initially but with all of the derailments scattered all over the nation that have been reported in this magazine over the past six weeks maybe upgrading and utilizing mothballed trackage might be a short term response while working out the bugs.