Bridges are a critical part of our transportation infrastructure. They come in a variety of styles, and are great for teaching STEM principles. This one is designed to be 3D printed. Here is some of the history of this particular design. 

Baltimore Truss – A Baltimore truss is similar to a Pratt truss design with additional bracing in the lower section to prevent buckling and add strength. The Baltimore Truss style bridge is a simple and very strong design often used for supporting trains.

Pratt Truss – In Boston, Thomas Pratt and his father Caleb Pratt designed a bridge truss structure that was to became a standard in bridge construction up to World War 2. It was able to span anchor points up to 250ft (76 meters) apart.

What is nice about this system, is that it is comprised of only 6 unique parts, which are all easy for a beginner to design in SOLIDWORKS or xDesign, it snaps together with no adhesives or fasteners, and none of the parts require supports in 3D printing so there is no waste! I think the Hot Wheels cars add a nice touch!