I really like the fact that people find my site useful and this example shows the true spirit of learning from the bridge building problem.

I got this email explaining the process this student went through. He actually built TWO bridges, one flat truss and one arch truss. He obviously did a wonderful job on both bridges and included some the specs in the email note.

Hello Again,
  
           I dont have a whole lot of info but I will give 
you what I have.  As you will see from the attached pictures 
we did two different styles of bridges. The  first was modeled 
off of your design. The other was a standardtruss bridge. Both 
bridges spanned 18 inches.  We constructed both bridges  with 
diamond round toothpicks and we cut the tips off of them for 
better surface area.
      We also used [**censored**] I didnt pay to  see what glue
you use but I figured  [**censored**]  would work well. I then
weighed the bridges. The arch bridge  weighed 78 grams and the 
truss bridge weighed 145 grams. A considerable amount  more. The
arch bridge ended up holding 50 lbs. for about 10 seconds before
it broke. That works out to be about 290 times its weight. The 
truss bridge held 60 lbs. which works out to be about 185 tiimes 
its weight. It was a very fun experiment and your website was a 
big help. Feel free to add any of this info to your website if 
you wish. If you would like to ask me anymore questions or see 
more pictures/videos just let me know.

 Thanks again. 

Eric

 

A shot while under Construction
There are four things I want to say about this bridge. First, it looks like Eric did a LOT of work and really is a smart guy. Second, I am not sure the arch is a catenary, it looks too rounded at the quarter points. Thirdly, I usually build the arch trusses FLAT, then assemble the bridge, so, just a different way to do it. And fourthly ( and most importantly) if Eric had used a different glue, his results might have been up to 100% improved! Yikes.