11.08.13

I Wanna Testify, Part 2

Posted in Uncategorized at 22:25 by Administrator

Video record of the two days of hearings is here and here.

The Day 1 PM session was devoted to a discussion of the crash-worthiness of the M8 cars involved in the derailment.   As much responsibility as Metro-North, and specifically Metro-North management,  must accept for the cause of the derailment, a responsibility it did not attempt to deny, exactly that much credit should be awarded to MNR, the car builder, Kawasaki, and the FRA (for the crash-worthiness regulation standards) for the performance of the M8 vehicle. There were no fatalities.  To my knowledge, there was no loss of life or limb.

Certainly, the crash speed, a combined 23 mph (1548 was stopped, 1581 was in emergency braking) was of primary significance.  Speed is the critical factor, with energy increasing by the square of the speed.  Design for crash worthiness, however, is based on a) probability of occurrence b) level of risk for each type of incident adjusted for probability of occurrence c) preserving the ability of the vehicle to provide the necessary service, the performance requirement, during normal, intended operation– the non-crash environment d) the accumulated knowledge from previous collisions e) the technical ability to actually construct and install the crash management feature.

“Progress,” such that it is, is necessarily and always incremental.  Short version:  You have to make the decision before you can get the information for further decisions.  Even if the M8 cars had not performed so “valiantly,” no reproach to MNR, Kawasaki, FRA would be warranted.  There was no negligence, no carelessness in the process of a) establishing the crash-worthiness standards b) design and specifications for the vehicle  c) construction of the vehicle  d) testing, validation, and acceptance of the vehicle.  I know a little about this, since I was involved in formulating some of the requirements for the M8 vehicle. I have been involved in the previous testing and acceptance of other systems and rolling stock while employed by Metro-North.

David Tyrell from the Volpe National Transportation Center, who I think knows more about rail vehicle crash management, and the history of the regulation,  than any other single person explained the process by which the collision strengths were determined, that  such determinations were a product of this calculus.

The NTSB board members were focused on the fact the “collision strength specification” for the B end (“B” is the rear end, derived from the “B for brake” as the handbrake is located in the “B” end.  Cars, including MU cars have an “A” end, as in “A is for head.”  Locomotives have an “F” end, as in “F for front,” and the F end is designated by the letter “F” applied to both sides of the F end) is approximately half of that required for the head end, the A end, of the vehicle.  A board member stated that, since the energy of a collision, even a head-on collision, is transmitted throughout the train, the train is “only as strong as its weakest link.”

Wrong.

The energy is not simply transmitted throughout the train.  The energy is dissipated, absorbed, mitigated as it is transmitted throughout the train even when “hardened” elements are not installed.  When crash energy management systems are installed at the head end of the vehicle, that dissipation, absorption, mitigation is even greater and provides greater security throughout the entire vehicle, throughout the entire area of occupancy as the M8s did in this derailment.

If such energy were not dissipated by the structure of the vehicle, then we would expect to see the deformation and destruction at the rear end of the car equivalent to that at the point of impact, and if that were the case, we’d have to do a lot more than get a new set of specs, we’d have to revise the very physics we’re using.

It’s always a surprise to me when those who talk about risk assessment, measuring risk, and responding appropriately to actual evaluations of risk seem to forget the fundamental elements of risk assessment– meaning exactly “what is the risk?”  The M8 configuration is that of back-to-back “married pairs.”  Control cabs on opposite ends, “B” ends  coupled together almost in a fixed arrangement.   The “risk” of the B end receiving impact energy equivalent to what the head end may receive is greatly reduced by the configuration of the equipment.

The B end is only “half as strong”?  OK, let’s assess that risk in this incident.  Speed at initial point of contact?  Approximately 23 mph, 33.73 ft per second.  Distance before the head end of 1581 contacts the B end of the head car, or second head car,  of 1548?  Approximately 85 feet, the length of one car.  Approximate rate of deceleration of the M8 in emergency brake, (based on previous experience with EMU pairs) 2.7 mph/sec,  3.96 ft/sec/sec; estimated speed of A end of 1581 impacting B end 1548, head car or second head car, 14.31 mph, or 62% of the speed at the initial A end to A end impact.  Because the energy is a factor of the square of the velocity, 62% of the original velocity transmits an impact energy at the B end  equivalent to 38% of the energy at the initial point of impact on the A ends.

Now, I’m only using paper and pencil here to make these calculations, and using simple math, but it seems to me that somebody made a damn good call, a pretty good assessment of risk in requiring that the collision strength at the B end to be half of the strength at the end.  It’s simple math, sure, but you know what? I’m a simple person.  Railroading is a simple business.  Railroading is all about simple math.  It’s time, speed, distance.

It was then and there that,  I heard  the all too mortal words of Frost in Aliens playing in my head: “Man, I’m telling you, I got a bad feeling about this drop.”

A member of the technical panel questioning the witnesses focused on the fact that when it comes to design specifications of the vehicle, and/or field modifications, the safety department of the railroad does not have input or right of review.  Let’s stop and think about that for a second.  Imagine we take a panel of safety experts, professional investigators, analysts, etc. and provide them with the  power to investigate, review, and recommend changes to policies, procedures, performance requirements, structures etc. on a railroad.  Now we formally establish this safety group,  invest them with the a status equal to that of the other groups on the railroad, and we call the group the “Safety Department.”  We send them the design specifications and field modifications for construction of a passenger rail vehicle and ask that board to evaluate, review, validate, and certify those specifications.  What would that department would do?  It would not itself evaluate and review that material.  That department, recognizing the limits to its expertise, would a) acknowledge it does not have the knowledge to discharge such an obligation b) turn to the engineering, design, and capital groups of the railroad to undertake the evaluation c) ask the mechanical department to ensure the compliance of the vehicle with all applicable regulations, MNR requirements, performance and operating standards…and recommend the hiring of outside parties to assist the internal departments of the railroad in these efforts– in short, the very same process that is currently used by railroads in procuring passenger equipment would be the result of engaging the safety department.

I had a bad feeling. I thought, excuse me, for speaking bluntly, that somebody was trying to make something out of nothing.  When that happens, I know that means something else that shouldn’t is going to be made into nothing.

I had a bad feeling. And there was nobody there to tell me “You always say that, Frost. You always say,  ‘I got a bad feeling about this drop.’ ”

 

November 8, 2013

 

Don’t touch that dial, the fun is just starting.  Coming Day 2.

 

 

 

 

 

 

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