I was also looking more closely at the aerial pictures of the derailment (I learned from an old railroader that they never said 'wreck', 'accident', etc to the press/public. It was *always* a 'Derailment'.) and it seems that the first 11 cars (including the idler boxcar) escaped the worst of the pileup, as did the last 9 or so cars. That left me wondering two things: 1) The TSB should be able to determine *fairly* easily if these cars had handbrakes applied, since there should be GIANT flat spots from the sliding wheels of cars w/applied brakes that were going 60+ mph before they derailed. The wheelsets seemed to have escaped the worst of the fire, so inspecting them should have happened early in the process. However, if the hand brakes were applied so that they just 'touched' the wheels instead of being 'cranked down', would the wheels still be free to rotate?
I can't imagine that the Transporation Test Center in Pueblo has ever done any testing of cars traveling 60 mph with the handbrakes applied, so question 2) gets into some train dynamics issues which are probably not well understood. If the first 16 cars (4 locos, the RCC caboose, idler car and 10 tank cars) had handbrakes applied and then later started rolling, the slack action between them should be somewhat reduced when they started moving i.e. they're not as close together as the remaining tank cars (w/no brakes) since the slack would've all run in on those cars as they headed downgrade. So, would there be a force discontinuity between the rear coupler of the last braked car and the front coupler of the first unbraked car or would the weight of the unbraked portion be sufficient to compress the slack in the rest of the consist?
Could that discontinuity be the reason why the first 16 cars made it through the 10 mph curve (which is probably safe up to 30 mph, at least in an engineering sense) and the pile-up started with the 17th (approx) car? The dispersion pattern of these cars seems to support this hypotheses (the idler car was still half on the main track, while the 16th car was flung way down the wye lead). This would also explain how the power separated and kept rolling through town...if the idler car were pulled backwards by the derailment and only broke a knuckle (or pulled a drawbar) on the last loco (or the front of the boxcar...), the locos would be free to keep on going.
If this is true, and more importantly, PROVABLE in a court of Law, could it help corroborate the engineer's claim about handbrake application?
I wonder if any of the high-tech operational software programs that the Big Boys use would allow a simulation like this? You'd need to have the track profile to input, but that info should be readily available....
Any large holes in my theory that I haven't noticed???? One thing I can think of is 'What was the slack condition of the last 60 cars when they stopped at Nantes? How much of the slack wound <typo that I missed-this should have read 'would'> 'rebound' after the train came to a stop on a descending grade? The dynamic behavior of the oil inside the cars (sloshing) is another big unknown (to me), but it's probably been modeled somewhere at some time.... <Added on 9/12- Thinking about this a little more, would the conditions after the initial stop change after the brake test? I'm thinking that they might, since *all* the airbrakes were still applied before the handbrakes were applied on the head end cars. The engineer would've released the train brakes while doing the brake test, so the slack on the train should've run in during a successful test.....Time to google 'Freight Train Dynamic Behavior', I guess...>
Last edited by RDG467 on Thu Sep 12, 2013 7:47 am, edited 1 time in total.