A typical US passenger train will be < 1,000 tons, whereas a freight train can easily be 10,000 to 15,000, possibly 20,000 tons.
The passenger train might be going faster - and the energy varies with the square of the speed, whereas momentum is linear with the speed - but it's got better set-up with designed Crash-Energy Management (CEM) zones, which the freight trains don't have. All they have is the rigid anti-climbers and collision posts in the nose, or the engine &etc. equipment in the long hood. And I understand that the supposed energy-absorbing feature of the early F- and GP- series EMD locomotives bending (not crumpling) just behind the cab was coincidental and happenstance, not designed-in (wouldn't be worth much in a high-energy collision anyway).
- PDN.
BaltACDThe tonnages of todays Class 1 freight trains posess more force in their momentum than virtually ANYTHING designed and built by man can withstand at the point of impact.
CEM on freight locomotives will not solve all problems but CEM can reduce the aftermath. Under some circumstances the FRA- Crashworthiness compliant freight locomotive might still have a quite intact crew cab but the crew didn't survive because of too high deceleration and impact. CEM can reduce both.
I don't know what you would do but I would never again use a car without CEM/crumple zone.Regards, Volker
VOLKER LANDWEHR BaltACD The tonnages of todays Class 1 freight trains posess more force in their momentum than virtually ANYTHING designed and built by man can withstand at the point of impact. CEM on freight locomotives will not solve all problems but CEM can reduce the aftermath. Under some circumstances the FRA- Crashworthiness compliant freight locomotive might still have a quite intact crew cab but the crew didn't survive because of too high deceleration and impact. CEM can reduce both. Regards, Volker
BaltACD The tonnages of todays Class 1 freight trains posess more force in their momentum than virtually ANYTHING designed and built by man can withstand at the point of impact.
Regards, Volker
Has getting killed by too much decleration ever happened with freight trains? I suppose it could if the tonnage is low enough, but generally, it seems that nothing can decelerate fast enough to injure the cab occupants because the tonnage just shoves everything ahead until it jackknifes, overrides, or disintegrates in a way that displaces it from the line of force of all the trailing tonnage. It seems to me that what kills crews is the cab disintegrating in this process. What is needed is an indestructible cab.
There is so much force that a sufficient crumple zone would take up the the entire locomotive several times over.
EuclidHas getting killed by too much decleration ever happened with freight trains?
Considering the damage that occurs during a collision between a train and an immovable object (or one of significant mass moving in the opposite direction), and that I don't believe there are any restraints in locomotives, I would say that the possibility of being killed (or significantly injured) by the sudden stop (or rapid decelleration) does exist.
It would be just one of many factors, as you note, and will depend heavily on the rate of decelleration. If we're talking a direct head-on, both locomotives will go from whatever speed to zero in a split second. If the crew sees it coming and heads for the floor they'll stand a better chance for the decelleration portion (ie, no face plant in the windshield). The structural failure of the cab and the rest of the locomotive is another story.
Given the level of destruction that will occur, I suspect it would be hard to specifically say that the secondary collision of the crewmember into the windshield was a significant factor in their injuries
The relative infrequency with which such collisions occur would preclude anything like seatbelts or airbags. Even padding on consoles, etc, would be useless in a major collision.
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One way I think it could happen is if you did actually have indestructible cabs in a head-on collision, and the locomotives totally disintegrated except for their cabs, and then the two cabs hit head-on.
There was an earlier thread about seat belts and restraints for train crews. They would only lead to more deaths. I would and so would many who replied to the thread that hitting the floor gives you a much better chance of suvival than selt belts or retrainsrs
EuclidOne way I think it could happen is if you did actually have indestructible cabs in a head-on collision, and the locomotives totally disintegrated except for their cabs, and then the two cabs hit head-on.
In you described case you would have a crumple zone.
In the 1995 the FRA researched a head-on collission of two trains, one with 5 locomotives and 92 cars, the other with 2 locomotives and 15 cars with combined velocity of 30 mph.
None of the locomotives were compliant with the AAR S-580 requirement of the times. The used this scenario as a baseline calculating impact on locomotive and occupants. Than the calculated the same scenario but with S-580 compliant locomotives, and ones with more rigid posts than required by S-580.
The baseline had the largest damage to the locomotive but the least impact on the occupants if the cab had stayed intact. But the cab got partly crushed.
The more rigid the post in the hood got, the higher the impact on the occupants:https://rosap.ntl.bts.gov/view/dot/8456/dot_8456_DS1.pdf?
The researched some additional measures like interlocking but not deformable anticlimbers. In that case the peak deceleration was 15g in the other cases 11g.
Just as a comparison the European standards allow a mean deceleration of 5g and a peak of 7.5g.
Another interesting read: onlinepubs.trb.org/onlinepubs/trnews/trnews286CrashTest.pdfRegards, Volker
When reduced to a smaller scale - the 'indestructability' of the skull is the cause of concussions in sports - the bones of the skull to an extent are indestructable in comparison to brain tissue. Severe impact and brain tissue crushes itself against the skull and there you have concussions and brain injury.
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The whole point of my having raised the issue of belts and elastic harnesses in these crashes is not primarily for restraint -- it is for impact management in the only place it really matters in heavy freight crashes. Decelerating the people at a rate that preserves them alive, while using "CEM" as a means of redirecting external force away from crushing whatever 'refuge' or cab zone the deceleration occurs in. Remember that CEM does not necessarily mean 'attenuation'; in fact some of the lateral-deflecting anticlimber designs explicitly use 'management' to mean vector change away from high-g-deceleration impact.
I highly suspect we will find the two men killed in the Cayce collision did not die of traumatic crush or rollover injury -- they died of prompt deceleration at high g. Even being in a padded refuge space, or dropping below even a capable long-travel controlled-crush zone, may not help in these situations. Certainly no amount of European-style nose or push-back coupler action would have helped much with this; it would only have staved off the lethal acceleration change as long as the crumpling was taking place. Proper "CEM" as the analogue of interior padding and active elements such as air bags is the way you save lives in such incidents. And, as in automotive practice, one effective way to get the controlled deceleration over full distance is to use pretensioned inertia-reel control in harness or belts, not to hold victims pinned for the squish, but to just stop them from hitting something harder than to bruise.
BaltACDthe bones of the skull to an extent are indestructable in comparison to brain tissue.
I think you will find that the proximate cause of most of these concussions is due to quite a different mechanism (but one that proves your point perhaps even better). What often happens is that a hard shock to the skull results in shock waves that are focused and reflected by the curve of the bone to where they cause the soft-tissue damage. Subsequent damage from the closed skull is much more associated with various forms of tissue swelling or fluid release than with direct damage from inertial deceleration.
There can certainly be inertial effects of the brain tissue inside the skull in high-speed trauma, but you will notice that most instances of high impact will result in skull fracture (and nothing more than concussion or some minor hematoma formation underneath) before gross traumatic brain injury -- this is likely not just a sampling artifact of analysis. The cushioning systems in the brain's surrounding tissues are reasonably good at cradling it against the kind of shock encountered in evolutionary survivable incidents...
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