Re: Tehachapi - 1999 incident Possible L over V?
Author: BOB2
Date: 06-20-2017 - 15:14
Unloaded, not nearly as much.....loaded, it would depend.
This is the kind of accident we started having with new light weight cars right behind the engine, and why proper placement of cars is part of making up a train today.
Back, in the days of "steamies" and early less powerful diesel power, and less powerful dynamic braking, when everything was a forty foot car, and trains weren't as heavy, it didn't matter much. But, as horsepower and adhesion began to rise, and trains got longer and heavier, and we started making cars longer and lighter (to reduce total tonnage and increase efficiency like with the use of spine cars....) we began to learn about the laws of physics, and the phenomena of L over V forces. It became noticeable that just plain more powerful locomotives, would "string line", or "compress", the train and just shove or lift those lighter cars, or even just normal empties, right off the rails. Or, as was the case with cabooses, more powerful locomotives would literally push them right off the rail when helping from behind. Among the lessons learned: empty spines behind locomotives, bad idea.........j
Hell, I've personally had empty pigs, low well cars, and spine cars "walk" right off the rails while shoving a yard cut through compound curves at the LATC/Shops a few times. So even there, with yard cuts, you had to be aware of using too much power at the wrong location. And, this happened so many times at the lower end, that we weren't suppose to shove in from the bottom when spotting pigs, ever.
Loads on the head end, empties on the rear...... Which is why, when you are eating the pulled pork and drinking a beer at Topock, or driving out I-40- you often look up or out your window, and see double stacks up front, TOFC in the middle, and empties to the rear.
Now, I can hear the howls of some of the foamers already, who will scream that this is not to be seen all of the time. No sometimes you get those solid stack trains with power on both ends. But, dealing with L over V isn't ignored anymore, proper distribution of loads and empties is now a required aspect of making up trains with certain tonnages/horsepower, and with certain specific car types, and the safe placement of loads and empties, because of a costly learning curve. Proper distribution of helpers/distributed power had the same safety/efficiency balancing learning curve....
The laws of physics are ignored at ones peril.....