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Subject: 
Re: World Record LEGO Bridge
Newsgroups: 
lugnet.trains, lugnet.build
Date: 
Wed, 23 Aug 2000 18:19:36 GMT
Viewed: 
2692 times
  
In lugnet.trains, Jeff Elliott writes:


Wayne R Hussey wrote:


First, to alleviate any rumors to the contrary, there is no support anywhere
along the span except the string. It was placed within a couple of inches of
the floor to provide a reduced amount of rail climb. The officiating took • into
consideration that the overall sag (over a distance of eight feet) was less
than one inch. There is a plan currently in the works to have it displayed • at
the GATS in Puyallup in November. For that display, there will be no changes
to the bridge - there will also be no doubt of its ability to span unaided.

<snip>
Wayne


Hi Wayne,

I'm sorry if my post sounded like I was challenging the authenticity of
your accomplishment - I figured that since your bridge was evaluated for
span length, it was able to stand unaided.  From my own (shorter-span)
bridge creations, I have some appreciation for the problems involved in
setting up such a large structure, and I had wondered whether you were
using supports while stringing it, etc.  The earlier responses cleared
up my confusion over the nearby monorail bridge.

My own experience is that the static load on a bridge span usually isn't
the big problem - it was when I tried driving two trains in opposite
directions that the induced roll and vibration would sometimes cause the
trains to jump track at flexing joints.  Then again, PNLTC uses bigger
trains than I do :)

Thanks for the info on your use on ZNAP - that'll be very helpful.

Take care, and congrats!

Jeff

I also had the problem of twisting/rolling at first when a train crossed. This
seemed to be reduced when I added the stretchers across the width of the span
at intervals, although there was still some roll. Even before the stretchers,
though, I never experienced a derailment. The above and below curved Znap
pieces which form a continuous interlocking 'S' were used to strengthen the
horizontal stiffness. Perhaps this also reduced the vibration you experienced.
Throughout the show, we had no trouble with short, medium or long trains
singly or over both tracks, in opposite or same direction. The whole thing
seemed very steady :)

Wayne



Message is in Reply To:
  Re: World Record LEGO Bridge
 
(...) <snip> (...) Hi Wayne, I'm sorry if my post sounded like I was challenging the authenticity of your accomplishment - I figured that since your bridge was evaluated for span length, it was able to stand unaided. From my own (shorter-span) (...) (24 years ago, 23-Aug-00, to lugnet.trains, lugnet.build)

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