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Locomotive Cabs, and Crew Safety in Collisions

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[quote user="Paul_D_North_Jr"] One minor point of difference: It seems to me that the 300,000 lb. shear strength requirement for each post is far larger than the load that could reasonably be expected to be developed or needed as a result of any collision with a highway vehicle - say, an 80,000 lb. GVW truck, even allowing for 'impact' - and as compared to the 65,000 lb. objects in the Appendix E crashworthiness specifications.  Therefore, I believe that was an early attempt - the regulation appears to date from 1980 - to provide crew protection against collision with other full-size railroad equipment.  <div style="clear:both;"></div> [/quote] Paul, In thinking about this a little more, I agree that a collision with a highway vehicle is not often likely to produce 300,000 lbs. (or double that for the two posts) of force, so I can see why you might conclude that the posts are intended for collision with railroad equipment.  However, the 300,000 lb. figure is not the actual required resistance of the collision post.  It is only the required shear strength of the post’s connection to the frame.    <o:p></o:p> I am not sure what they have actually executed in the design of the posts to fill in the missing information of the specification.  I assume that they have met the 300,000 lb. spec. for shear at the base.  They may even have achieved around 300,000 lbs. of bend resistance right up to the top, even though the specs. do not address that aspect of the design.  Nevertheless, it may have seemed like a reasonable way for the builder to interpret the spirit of the regulatory specification for the posts.  <o:p></o:p> If the posts are that strong, that would certainly seem like overkill for just automobiles, but probably not overkill for heavy trucks, especially trucks carrying pre-cast concrete components, structural steel, steel plate or coils, or blocks quarried stone, for instance.  On the other hand, I would say it is way less than what would be required to resist the force of a collision with railroad equipment.  The 300,000 lb. figure for shear strength at the base would be more than enough for collisions with locomotives or rolling stock.  But I think 300,000 lbs. of bend resistance four or five feet up on a free standing post would way less than what is needed.
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