This post features one of the most intricate reader submitted bridges I have ever received. This is a model of the Hell Gate Bridge built by High Iron Models. Excellent work.

A very nice looking Balsa wood bridge sent in from one of my readers. This bridge uses gussets and pin joints and spans 18 inches.

Garrett- Jobs well done – interesting site and information! We built a 1/8″ scale model bridge just like the bridges we build for production. We successfully loaded it with 345 pounds with the weight being distributed all the way across the middle. Do you know of a formula where we can figure out that weight [...]

This bridge is supporting 191lbs of weight. It didn’t break, that was all the weight we could fit in the trash can. I believe this is close to the maximum load it could hold because the platform the jig is resting on was significantly bowed. The rest of the structure was rock solid. The construction of the bridge is popsicle sticks

We run a comp here at Albury High in Australia for our Yr 12 Engineering Studies students involving max. 50 popsicle sticks, PVA wood glue and 2m of extra strong thread.  Structures have to span 400mm and are centrally loaded.  Here’s a photo of our 2010 winner which weighed in at 69 grams and held 58kgs giving an efficiency using the formula on your website if i used it correctly of around 12000!

These are some pictures of a bridge I built mainly out of boredom, but also since I have an interest in engineering. It’s a large cantilever bridge, meaning it has two arms that extend beyond their piers that hold up a center suspended span. It’s 10′ 2″ long and as of right now is hanging across my bedroom ceiling

Nic’s design held a weight of 224kg and had a final efficiency of 1020. It did not shear or snap at any member, but bowed in the second third of member C-E. This member did have angled bracing to stop bowing and this brace did not snap it was only the glue joins in this brace that failed. The truss ballooned out at the point when 2.2kN of force was applied. It was at this point that the test was stopped

It’s taken me just under 48 hours to get this far. Although i wouldn’t say its completely finished.. it’s a good as. I might just polish it off with a lick of paint and other aesthetically pleasing type things. As you can see, I’ve modelled it on the Pratt Truss. Although, I didn’t do any “real” plans, just rough drawings

Garrett’s Note: I am not sure why the author called this a toothpick bridge, as it looks more like Balsa wood. The author did not not give any information about this bridge, which is unfortunate. I would have like to known about why he chose this design, and what the bridge was trying to accomplish.

We found that it holds 5lbs so far and potentialy more, considering our first bridge broke with a large ball of string as the weight and our second broke with a coke can. I think our success rate was pretty high