Nice Hump

Arkansas, 1908*:

The description in the text calls it – correctly – a camelback through truss, but that’s incomplete. The most important distinguishing characteristic of a bridge is the web layout: the pattern of verticals and diagonals. In this case, the three panels at each end of the bridge are those of a Pratt truss, while the four center panels are double-diagonal, indicating that someone was willing to do the extra work required for a statically-indeterminate truss analysis.

We don’t build short truss bridges anymore, as labor costs now govern rather than material costs, so it’s easy to forget how light and fluffy airy they can be.

We also no longer commonly use pin connections or laced built-up members.

*Also, its name is Nimrod.