XPost: uk.railway   
   From: Anna@noyd-dryver.com   
      
   hounslow3@yahoo.co.uk  wrote:   
   > On 28.12.17 14:30, Anna Noyd-Dryver wrote:   
   >> Phil Kane  wrote:   
   >>> On Wed, 27 Dec 2017 13:12:58 -0000 (UTC), Anna Noyd-Dryver   
   >>>  wrote:   
   >>>   
   >>>> After the old track and sleepers are removed, it appears from that picture   
   >>>> that the old ballast is being removed too, following which I would guess   
   >>>> that better drainage will be installed, then there's usually a membrane of   
   >>>> some kind to keep the sub-soil out of the ballast, this will be followed   
   by   
   >>>> the new ballast and finally the new sleepers and rails.   
   >>>   
   >>> Thank you very much for that explanation of the work to be done.  What   
   >>> is not evident to me from the picture is whether the line was on   
   >>> elevated structure, on the surface, or underground - the last two   
   >>> would entail digging.  I am one-third of the way around the world and   
   >>> don't remember those details from my one and only visit to London 50   
   >>> years ago!   
   >>>   
   >>   
   >> Even on an elevated structure, replacing the ballast will involve digging!   
   >>   
   >> This picture posted earlier in the thread   
   >>    
   >> clearly shows line in a cutting   
   >>   
   >>   
   > Elevated sections on the New York City Subway don't have ballast, AFAIK,   
   > They just run on steel structures.   
   >   
      
   I should have added the word 'often' before 'involve' ;)   
      
      
   Anna Noyd-Dryver   
      
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