On Thursday, 12 February 2015 19:02:46 UTC+1, peterw...@hotmail.com  wrote:   
   > In the recent Metro North collision I was surprised to hear that, in   
   addition to the driver of the car involved,there were five people killed ON   
   THE TRAIN.  Some questions:   
   >    
   > 1. In designing the iconic FT freight locomotive and E series passenger   
   locomotives, Electromotive put a hood-like structure on the front specifically   
   to give some protection to the engineer and fireman in the event of a   
   collision at a grade crossing,    
   and virtually all subsequent American locomotives have continued this   
   practice. Is there any requirement for grade-crossing protection on   
   self-propelled motor unit passenger cars?   
      
   One risk with this line of thinking is that if you focus too strongly on one   
   failure mode, solutions that reduce harm in that situation may increase it in   
   others.  The best way to reduce deaths and injuries in grade crossing   
   collisions is to prevent the    
   collisions.  This might mean closing less used crossings, grade separating   
   where possible, or putting in positive singalling control on others (ie where   
   the crossing is protected by railway signals that aren't cleared for the train   
   until the barriers are    
   down and the crossing positively checked to be clear).   
      
   > 2. In the accounts I've read, the lead unit on the Metro North train was set   
   on fire by gasoline from the fuel tank of the Mercedes Benz SUV. Barring the   
   few battery powered cars in service, every vehicle hit at a grade crossing has   
   a fuel tank; in the    
   case of a semi truck there might be as much as three hundred gallons of diesel   
   oil onboard. Does the design of a locomotive or motor unit incorporate any   
   protection from this?   
      
   Most passenger trains are built to quite exacting fire resistance standards,   
   particularly where they operate in long tunnels (eg in mountains, under sea   
   tunnels or under-city tunnels).  There is only so much you can do in the event   
   a train is engulfed in    
   burning fuel, though.  Again, the best protection is that described above.   
      
   > 3. In the accounts, the electrified third rail broke, came loose from the   
   track structure, and impaled the lead unit, whereupon arcing from the rail   
   ignited the gasoline from the SUV. With modern welded rail track, broken rails   
   are a known and feared    
   failure mode. Does a locomotive or motor unit incorporate specific protective   
   features against against being impaled by a broken rail, either a main rail or   
   a third rail?   
      
   I doubt there are specific measures for this.  This is an area where   
   protecting against one risk may increase others: if you increase the   
   structural strength of bodywork to protect against a broken rail impalement,   
   that extra weight will increase the    
   energy and hence risk in train-on-train collisions, and may impair the ability   
   of the structure to absorb collision energy in a way that is less harmful to   
   passengers.   
      
   Railway accidents are generally quite rare, to the point where each one is   
   effectively a statistical anomaly.  It therefore is very important to   
   recognise that, while the failure mechanism in one particular accident needs   
   to be considered, there are just    
   as significant failure mechanisms that happen to have not manifested   
   themselves simply due to random chance.  It is important (and difficult), when   
   fixing the failure mechanisms that have manifested themselves to avoid making   
   the other failure mechanisms    
   worse.   
      
   Robin   
      
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