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posted by Fnord666 on Friday April 05 2019, @11:17AM   Printer-friendly
from the good-luck-with-that dept.

Morningstar:

Freight railroads generally have operated the same way for more than a century: They wait for cargo and leave when customers are ready. Now railroads want to run more like commercial airlines, where departure times are set. Factories, farms, mines or mills need to be ready or miss their trips.

Called "precision-scheduled railroading," or PSR, this new concept is cascading through the industry. Under pressure from Wall Street to improve performance, Norfolk Southern and other large U.S. freight carriers, including Union Pacific Corp. and Kansas City Southern, are trying to revamp their networks to use fewer trains and hold them to tighter schedules. The moves have sparked a stock rally that has added tens of billions of dollars to railroad values in the past six months as investors anticipate lower costs and higher profits.

Calling all Railroad Tycoons...


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  • (Score: 2, Troll) by Runaway1956 on Friday April 05 2019, @01:43PM (17 children)

    by Runaway1956 (2926) Subscriber Badge on Friday April 05 2019, @01:43PM (#824878) Journal

    No, hitting a car doesn't slow the train, at all. Doesn't even slow it down when it hits a loaded 18 wheeler. It's anybody's guess how much of the car, or truck, you actually find after the dust settles.

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  • (Score: 0, Troll) by Anonymous Coward on Friday April 05 2019, @02:15PM (11 children)

    by Anonymous Coward on Friday April 05 2019, @02:15PM (#824902)

    > doesn't slow the train, at all
            doesn't slow the train appreciably

    Never studied Newtonian mechanics, did you? F=mA is damn reliable (at the macro level) and the train must slow down a tiny bit.

    • (Score: 2, Disagree) by Runaway1956 on Friday April 05 2019, @02:42PM (4 children)

      by Runaway1956 (2926) Subscriber Badge on Friday April 05 2019, @02:42PM (#824925) Journal

      Perhaps. Or, maybe the train just absorbs all the energy, resulting in some dents and crumpled metal. You're not going to measure any loss in speed.

      • (Score: 0, Informative) by Anonymous Coward on Friday April 05 2019, @04:38PM (2 children)

        by Anonymous Coward on Friday April 05 2019, @04:38PM (#824991)

        Momentum is conserved, train is minutely slowed down. Git edumacated son!

        • (Score: 2) by Runaway1956 on Friday April 05 2019, @04:43PM (1 child)

          by Runaway1956 (2926) Subscriber Badge on Friday April 05 2019, @04:43PM (#824993) Journal

          I think that's exactly what I said - you're not going to measure any loss in speed.

          • (Score: 0) by Anonymous Coward on Friday April 05 2019, @08:47PM

            by Anonymous Coward on Friday April 05 2019, @08:47PM (#825107)

            Nope.

            "Or, maybe the train just absorbs all the energy, resulting in some dents and crumpled metal. You're not going to measure any loss in speed. "

            A human eyeball may not be able to see the loss in speed on the speedometer, but there will be a loss in speed. I wouldn't have made a fuss if you hadn't started with "maybe the train just absorbs all the energy" which makes it sound like there would be absolutely no change in speed. Conservation of momentum says that is incorrect, though your statement about no loss in speed is "basically" correct. Important to realize those distinctions.

            Momentum in mass * velocity, so "total momentum" = (M1 x V1) + (M2 x V2)
            The masses don't change and after the collision the car is traveling a lot faster than zero so the momentum was transferred from the train to the car, thus the train velocity decreases. The reason it is not very noticeable is because the mass and velocity of the train are so much higher that the momentum lost is a tiny percentage but it will be there.

      • (Score: 2) by realDonaldTrump on Friday April 05 2019, @09:52PM

        by realDonaldTrump (6614) on Friday April 05 2019, @09:52PM (#825145) Homepage Journal

        I'm a New Yorker and some days we have 2 or even 3 folks getting hit by the subway cars. It makes the news but, it's not big news when that happens. And, not a big deal for the Transit Authority guys. They run the windshield wiper, they do the little spray and life goes on, you know? A lot of the cars look rusty in the front, trust me it's not rust. And I guess you could have Einstein come in their with a very special instrument to measure the speed when somebody's getting whacked, I don't know.

        But I'll tell you this. Nothing stops the Trump Train. And, nothing slows it down!!! 🚂

    • (Score: 2) by RS3 on Friday April 05 2019, @05:20PM (5 children)

      by RS3 (6367) on Friday April 05 2019, @05:20PM (#825011)

      You're right on an absolute level. Here on Earth, we use sensors, which are usually electronic, and the change in train's kinetic energy is often less than one valence electron knocked loose, so kind of immeasurable. But I know you'll have an absurd response, so I'll eagerly keep checking back for the moronic wisdom that I so desperately need that you'll dispense.

      • (Score: -1, Troll) by Anonymous Coward on Friday April 05 2019, @09:01PM

        by Anonymous Coward on Friday April 05 2019, @09:01PM (#825117)

        I would have thought that on a tech/science site that such pedantic points wouldn't be seen as some kind of personal attack, but OK Runaway's alt account!

      • (Score: 2) by realDonaldTrump on Friday April 05 2019, @10:10PM (3 children)

        by realDonaldTrump (6614) on Friday April 05 2019, @10:10PM (#825151) Homepage Journal

        This is not an Einstein thing. This is train. Listen to Runaway1956. He knows. Train runs on time -- does not slow down AT ALL!!!!

        • (Score: 2) by RS3 on Friday April 05 2019, @10:48PM (2 children)

          by RS3 (6367) on Friday April 05 2019, @10:48PM (#825165)

          I don't think you understood my comment; I was responding to an AC mega-troll. I try to never respond to them unless they're positive and contributing to the discussion.

          I agree with Runaway, JoeMerchant, and others here. AC was making inane comments about F = MA, etc. I'm an EE, which means I've completed many physics courses and qualify as a junior physicist. As an EE I'm inherently practical, and my point was that a train hitting a car would make an almost immeasurable change to the train's kinetic energy. In fact, I don't even see any practical reason to try to measure it. On to better things!

          • (Score: -1, Troll) by Anonymous Coward on Saturday April 06 2019, @12:25AM

            by Anonymous Coward on Saturday April 06 2019, @12:25AM (#825201)

            Look again at what you said:

            > a train hitting a car would make an almost immeasurable change to the train's kinetic energy. In fact, I don't even see any practical reason to try to measure it. On to better things!

            And this is in the context of cow catchers. Do you realize cow catchers are there not to spare the cow, but to spare the train? Do you realize that cars weigh more than cows, that the change to the train's KE is going to correlate to damage at the front-end, which can practically have huge impact (yuk yuk a pun)?

            What you said is kinda dumb.

          • (Score: 0, Interesting) by Anonymous Coward on Saturday April 06 2019, @01:28AM

            by Anonymous Coward on Saturday April 06 2019, @01:28AM (#825228)

            True brilliance, calling a technical correction "mega troll". Typical conservative, triggered by people explaining reality.

  • (Score: 1) by Improbus on Friday April 05 2019, @05:47PM (4 children)

    by Improbus (6425) on Friday April 05 2019, @05:47PM (#825027)

    If it hits a truck, depending on what it is carrying could cause the train to derail. Picture a GIANT electrical transformer on a lowboy trailer. That would cause a bad day for EVERYONE.

    • (Score: 2) by canopic jug on Saturday April 06 2019, @05:17AM

      by canopic jug (3949) Subscriber Badge on Saturday April 06 2019, @05:17AM (#825299) Journal

      I'll clearly need to make better use of the /sarcasm tag for markup in the future.

      --
      Money is not free speech. Elections should not be auctions.
    • (Score: 2) by RS3 on Saturday April 06 2019, @07:43AM (2 children)

      by RS3 (6367) on Saturday April 06 2019, @07:43AM (#825318)

      That's a great point. Most of the derailments post collision are due to chunks of debris on the tracks, and sometimes the collision debris wedges the track loose enough to cause the derailment. I've often wondered if there would be fewer derailments if at least locomotive wheels had flanges on both sides, or maybe one axle had inside flanges, then the next axle had flanges on the outside of the track. Maybe someone knows this.

      Yes, a locomotive hitting something big and solid like a transformer (or a 10,000 HP motor: http://www.mgmelectricalsurplus.com/Details/Motors/AC%20Induction%20-%20Squirrel%20Cage/107.php [mgmelectricalsurplus.com]) would cause a big problem. In USA, the maximum weight for a "lorry", or 18-wheeler tractor-trailer is 40 tons (36 metric tons). One of the biggest locomotives ever built can be 210 tons (190.5 metric tons). A 100 car freight train can weigh 14,000 tons (12700 metric tons). So the lorry would weigh 0.28% of that train.

      • (Score: 1, Informative) by Anonymous Coward on Saturday April 06 2019, @12:35PM (1 child)

        by Anonymous Coward on Saturday April 06 2019, @12:35PM (#825351)

        > One of the biggest locomotives ever built can be 210 tons (190.5 metric tons).

        Since the connection between loco and the rest of the train has some slack in the couplers[1], let's look at just the loco. Consider a medium SUV in USA can be easily 2.1 tons. That is a mass ratio of 100:1 and if the collision was "perfect" the loco would decelerate at .01 g for the instant of the crash.

        [1] Slack comes from loose tolerances in the couplers. This is not just a side effect of manufacturing tolerances, it is required to get the train started--the loco tugs on one car and a moment later that car tugs on the next one. To stretch the analogy, it's like ripping a phone book in half, to win you have to start the tear on each page separately.

        • (Score: 2) by RS3 on Saturday April 06 2019, @03:48PM

          by RS3 (6367) on Saturday April 06 2019, @03:48PM (#825407)

          Thank you! A non-troll AC. I started a lengthy reply, involving coupler slack (which is intentionally up to 1.5 feet per coupler, or 3 feet per coupling), car weights, collision forces, brake force variation, etc., but deleted the lengthy reply (because I don't have enough time to do more research / calculations) after learning 2 things:

          1) collision force calculations are complex and I'm not sure if a simple 100:1 -> 0.01 g. You can certainly do a simple calculation based on conservation of momentum, but the peak force will depend on energy-absorption by various structures which will crumple. For example, many of the large locomotives have a pair of stairs in the very front. The 10,000 HP 45 ton motor won't crumple much, but the point is that anything at all will greatly reduce the peak impulse of the collision. If the locomotive is moving relatively slowly, and there's appreciable crumple "stuff", the g force will be less because it's happening over some amount of time.

          But neglecting the obviously short duration of crumpling, you still have:

          2) car coupling compression is a total unknown. They could be in full stretch, full compression, or unknown, so we'll never know the full peak energy of impact of a 100 car 14,000 ton train hitting a 45 ton motor unless we put accelerometers in locomotives.