Scott G.

I am not sure where my 12 year old son came up with the idea for bridges for science fair, but he wanted to see whether an Arch or Beam bridge was stronger. In this electronic age, my kids have not built very many models. I had ideas in my head how we were going to build them, but decided to Google the world for help when I came across your website. Thank you!

My son viewed a beam bridge being stronger because they are more common. As you state on your website, there are so many variables. The plans were very easy. I helped my son tape a few copies to a board so he could build two bridges at a time. My son did a great job for his mechanical ineptness! We loaded from the bottom with a 5 gallon bucket. I found it necessary to use two hooks to even the load. We used some free weights from dumbells and then rock salt. Realized after the first failure we needed safety glasses! Enjoyed watching the bridge change shapes as it was distorted.

We found the beam bridge held about 19 kg and the arch held about 25 kg. My son did not do as much research as I would have liked. I forget he was only 7th grade. I tried to explain to him that the beam is probably used more than arch due to construction costs and practicality, but there are a fair amount of arch bridges out there.

His score for the project and presentation was 96 out of 100.

Again, I really enjoyed your website and appreciate your help and expertise.