I respect the mechanical engineering point of view. > As a mechanical engineer, my professional opinion is that trains should not be derailing, period. I was

I respect the mechanical engineering point of view. > As a mechanical engineer, my professional opinion is that trains should not be derailing, period. I was also trained as an engineer. Part of that training is understanding probability and risk. There is going to be some risk of derailment. How do you go about deciding the acceptable risk of development? Have you done such a calculation before? What is it based on?