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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...
(Score: 2) by RS3 on Saturday April 06 2019, @07:43AM (2 children)
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)
> 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
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.