Question/Dilemma about High Bridge Construction...?

[NW Mailing List]

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<http://nwhs.org/mailinglist/2014/20140507.hb.22.jpg>
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>

> 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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