Wonder how well it would work in real life? Here’s a version erected out of construction lumber in Stuttgart, Germany, with the city’s Mayor being driven across it.
Ponte di Leonardo
And in Denmark.
Modern bridges are built with high-strength materials and carefully-selected fasteners. Design considerations include the weight of the bridge and the load it carries as well as stresses caused by wind and earthquakes. Bridge components are subject to tension (pulling), compression (pushing), torsion (twisting), and shear (forces that act at an angle).
Leonardo’s arched bridge is brilliant in that the design is self-supporting, requiring no fasteners. Leonardo envisioned using nothing but gravity, friction, and large logs to build his bridge. The bridge’s own weight holds it together. As weight is added to the bridge, its structural elements are forced more tightly together, making it even stronger!