Question/Dilemma about High Bridge Construction...?

[NW Mailing List]

I think subsequent replies to this original posting may have missed the point of the question when they only point out that the track on High Bridge was offset to one side of the trestles in order to provide for a second track,even though that may be true.  As I understand the original question it is: Why do construction photos show a track in the center of the trestles --not offset to one side?

Gordon Hamilton
  ----- Original Message ----- 
  From: NW Mailing List 
  To: NW Mailing List 
  Sent: Wednesday, May 07, 2014 9:03 AM
  Subject: Question/Dilemma about High Bridge Construction...?


  Guys
  Can you help unravel this mystery?
  Why are the High Bridge Rails off to one side of the towers now as opposed to directly in the center of the towers originally as seen in
  the Vail pics attached below.

  Bob Flippen

  Moderator:
   http://nwhs.org/mailinglist/2014/20140507.hb.3.jpg
   http://nwhs.org/mailinglist/2014/20140507.hb.4.jpg
   http://nwhs.org/mailinglist/2014/20140507.hb.5.jpg
   http://nwhs.org/mailinglist/2014/20140507.hb.22.jpg
  ------------------------------


    In Vail's photos, it appears that the bridge spans were laid in the center of the towers, as is clearly shown in the first attached file
    (and many of his other photos).  The girders of the span run right across the two stiffeners (or whatever they are) in the center of the
    cross-girder at the top of the bridge bents/towers.

    BUT...  today the bridge spans run along one side of the towers, as clearly shown in the 2nd and 3rd attachments.  The spans do not run
    directly over the two stiffeners in the center of the cross-girder.  And, in fact, in Vail's photo of the new and old bridge together (4th
    attached), the girders of the new bridge clearly rest on the outside of the tower.  This makes sense since the bridge was constructed to
    support two tracks.

    So what am I missing???  I looks like the constructed spans on which the steam crane rode to install the top section of the bents and the
    next bridge spans isn't in the same position as the final bridge spans!  Were these spans temporary to support the installation, and then
    moved?  Nothing is mentioned of moving the spans later, and that seems like it would be a waste of time and energy.  And Vail's photo of the complete bridge shows the spans in place on the towers as we see them today.  I'm obviously missing something!




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