Designing my layout, I wanted to incorporate different types of bridges (I suppose that’s a thought of many model railroaders), but I wanted to design some of my own bridges in a freelanced but believable way. There are a number of concrete arch bridges in my area of NW Philadelphia including the Walnut Lane Bridge and the Henry Avenue Bridge, both Highway spans but seemingly constructed very similar to many railroad bridges of the same type. I also referred to the terrific book “Bridge and Trestle Handbook” by Paul Mallery to keep me building a basically sound engineered structure.
The Drawing shows my design for a concrete arch bridge to span a gorge that will be right in the front of my layout.
The photo shows the form I built to cast the bridge (actually half the bridge) as two castings back to back will form the bridge.
The form is made from Wood and sintra.