Loose Stone Bridge

Building a load-bearing bridge from a few loose stones? Using a template, the stones can be put together in the right order to form an arched bridge; this can even support an adult person when the roadway is laid on top. The advantage of these arched bridges is that - with an ideal construction - no tensile forces occur, only compressive forces, which are transmitted to the subsoil. This gives the bridge enormous stability - without any glue or mortar.