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RailroadDoc: 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." But what about a capacity basis? The next evening, I unfortunately was not able to attend an associated presentation at Northwestern that attempted to make a case for PTC on a capacity-increase basis. The consensus of six experts in the audience I talked to the next morning (all of whom would very much like PTC to work, mind you, because it would help them compete with trucking), was that PTC cannot economically increase capacity. Maybe if the cost came down to 10% of estimates. But there are still many technical problems with PTC that haven't been satisfactorily resolved, and no one knows the cost that will be incurred. You raise many interesting ideas in your proposal for using GPS. None of them will work, in my experience, because they all violate authority to occupy a main track, which is the fundamental concept of railroad operation. I'll address just a few salient points. 1. It's suggested that the value of this system is that trains could operate on three-mile headways instead of 10-mile as at present. Actually, trains already operate on three-mile headways, or even less. The headway depends on the braking distance of the train, and block signals are spaced accordingly: two or three miles on a typical Class I main line, maybe one mile on a heavy-rail commuter line. Theoretically, you could operate two trains running at 70 mph, 100 feet apart. But that gets you nowhere: at the end of the line, as everything enters a terminal, the trains are only going to go through the switch so fast. (This is the "fleeting" fallacy -- running a bunch of trains in one direction, then a bunch in the other, merely overloads terminals and makes terminals grossly inefficient because the traffic appears in spurts.) No one anticipates being able to do much about tightening train spacing with PTC except in the case of a line with trains of widely divergent braking distances, such as 40-mph drag freights and 125 mph passenger trains. But that is such a prohibitively uneconomic way to run a railroad that no one wants to do that. The limits to track capacity are not too many trains -- it's finding big blocks of time to maintain the track. UP's triple track in Nebraska essentially consists of two active tracks, and one down for maintenance. A frog in a crossover or switch on a busy main line will require 4-6 hours of welding time a week to add back metal that's been worn off. Rail on a heavy tonnage line, on a curve, is good for maybe two years. And so forth. PTC won't help you there. Once a single-track line gets past 70 trains a day, it becomes virtually unmaintainable. Temporary speed restrictions appear, capacity crumbles, time to maintain track becomes even more scarce, and a vicious cycle ensues. 2. Fuel economy could conceivably be improved if a train was instructed to run at, say, 30 mph for the next 10 miles to time it for a meet, rather than racing up to the red light. Rather than hire an army of train dispatchers to administer this, much effort has been spent on software to automate the process. It's turned out to be beyond the ability of the software engineers to write. One Class I, which I will not embarrass by mentioning, has spent more than $50 million attempting to write that software. The software miserably failed in every test, some of which I witnessed firsthand. (Even the very simple "Automatic" software that equips most dispatching consoles, which self-clears signals and sets up meets on single track, does all sorts of dumb things. Most dispatchers will not use it.) 3. Speaking as a former train dispatcher, the elements of the system you propose would increase the workload on the dispatcher by 100% to 200%. (I'm sure my friends in the craft would all applaud you, as doubling or tripling the ranks would instantly boost them so far up the seniority roster they could bid in that cushy afternoon job they want.) Labor costs would wipe out the savings, if there were any. 4. I doubt that an ATC has more information on you and your aircraft than a train dispatcher has on his or her trains. (They're not called controllers in the U.S., though they are in Canada.) I've never visited an ATC office, nor do I know much about that craft. However, I do know train dispatching quite well, and I think you would be deeply astonished at the information at a dispatcher's fingertips. Moreover, I knew everything about my trains I needed to know -- knowing the location of a train within 20 feet is of little or no practical value, and if I really want to know that, I can call the train. 5. Current methods of rail operation are summed up as "protect, then authorize." No train, man, or machine is given authority to enter a main track until the dispatcher has protected that movement. That protection is absolute, and can be violated only through willful action or negligence (such as running through a signal indicating Stop without stopping). In other words, no matter what happens -- a dispatcher can lose all control over the signal system and all radio communication, or the whole signal system can all go dark -- and Trains Will Not Run Into Each Other. They're protected. (And yes, this happens often. It happened to me every hot, humid, rainy night in the Ozarks.) Your system includes numerous "authority take-aways," which are by definition not fail-safe, whereas current methods of railroad operation specificially exclude authority take-aways. My suggestion is to obtain a good book on railroad operation methods, such as Elements of Train Dispatching, Vols. 1 and 2, and a rule book, learn them, and see if your ideas still fit. It would also definitely help you to spend a year working as a train dispatcher or in train service to understand the problems first-hand. I certainly did not understand how railroads work until I worked for one. As one good friend of mine put it, "I thought I knew about railroads until I went to work for one. Then I found out I didn't know ****." After a couple of months on the console, I called him up one night and said, "I see what you mean ...." By now, you've probably noticed that technical solutions proposed in this and other forums are regularly shot down by railroaders. It probably frustrates you to get answers that boil down to "Because." No one is trying to ignore you (in contrast, the effort to which people go to answer questions is quite large), but because a full answer to almost any of these questions can't be written in an hour. In truth, the only way you'll get a full answer is through years of education. Personally speaking, I would not even attempt to propose an alternate form of train control without first arming myself with a degree in electrical engineering, and surrounding myself with a team of experts with long experience. Railroading is a technology that worked out most of its fundamental questions over 150 years ago, and railroads are very good at accepting, adopting, and implementing new techological solutions the instant they appear. For example, when EMD's FT demonstrator appeared, most of the railroads that tried it knew within a matter of 24 hours that steam was deader than a dinosaur. Less than one day's experience with the diesel to know it was time to throw out an entire way of life, and they couldn't wait to do it! When you get your July issue in a couple of weeks, read the article on B&O train control experiments in 1965. It goes right to the heart of your proposal, and describes why it won't work. On the other hand, railroads have severe cultural and ideological problems that are obvious to the outside, and outside solutions would work (assuming you have the power and imperviousness to matters of consience of Josef Stalin). But that's because cultural problems are human in form, and it takes no technological knowledge to understand them, only knowledge of human nature. Technical problems require techical expertise.
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