A creek on the farm needs a crossing. The Amish build simple timber bridges without engineering degrees.
Simple Beam Bridge
Two thick logs (30–40 cm diameter) as main beams. Length = creek width + 1 meter each side (bearing). Cross-beams topped with deck boards (5–8 cm thick), nailed or screwed.
Foundation
Beam ends rest on stone or concrete abutments. Not on soil — they'll rot. Stones above flood level. Under beams — oak pads (oak rots slowest).
Wood Selection
Main beams: oak, larch (don't rot in water). Decking: any dense wood. Softwood (pine) — treat with linseed oil or tar.
Load
Horse and buggy — 1–2 tons. Two logs 35 cm diameter, 5 meters long support 3–5 tons. With margin. For heavy loads — add a third beam in the center.
Lifespan
Untreated oak bridge — 15–20 years. Tarred — 25–30. Decking replaced sooner (10–15 years), beams last longer.