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[quote user="Paul of Covington"]This is what bugs me: the calculations for stopping the train are figured from the time the people first came into view. [/quote] As the media reported the stopping distance calculation was provided by the defense, I speculate they wanted to say that even if the engineer had made the maximum service application the train wouldn't have stopped in time. In such a calculation you often use the best possible circumstances. But then you have to be clear about the imponderabilia. In another forum a read the statement of an engineer that following calculation would be a good approximation for the stopping distance: s [feet]= V² [mph] With 56 mph s would be 3,136 ft. So the 2,135 ft from my backwards calculations seems to be on the short side. I believe the engineer thought for a long time the people would come off the bridge in time or be safe on the walkway of the bridge. It retreats between the truss members as can be seen at 17'': <a href="https://www.youtube.com/watch?v=AgL39l6KrdQ">https://www.youtube.com/watch?v=AgL39l6KrdQ</a> When he realized his wrong jugdement (because of the wrong reactions/actions by the film crew) it was too late to reduce the speed considerably by braking. As long as we only know the statement "train would have stopped 2 seconds after impact) everything stays speculative. Calculating stopping distances is quite complex. But when you know the train composition car by car and all other train details there is software today to calculate the stopping distance. You still have to make assumptions but by varying them you can get quite realistic results. Mass doesn't have an influence as the braking power is mass dependend too and is eliminated from formulars. Regards, Volker
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