How Bridges Are Built

Our research on the design of bridges as designed by the State Engineer's Office.

Historical Data on Bridge Construction

from Design of Highway Bridges by Milo S. Ketchum,

1908, and 1920 editions.

Parts of a Bridge

Schematic diagram of a through Pratt truss, illustrating the various members and their names. Members in compression are in heavy lines, tension in light.

Definition of a truss:

A truss is a framework composed of individual members so fastened together that loads applied at the joints produce only direct tension or compression. The triangle is the only geometrical figure in which the form is changed only by changing the lengths of the sides. In its simplest form every truss is a triangle or a combination of triangles. The members of the truss are either fastened together with pins, pin-connected, or with plates and rivets, riveted.

Types of truss bridge:

We also have a page tracking the design of bridges as designed by the State Engineer's Office.

Through types. Note: the type shown at (f) is commonly referred to nowadays as a Parker Truss, after the railroad engineer who first designed the type. Camelback is today reserved to refer to a Parker truss with only 5 slopes.

Short or Pony truss types, including beam spans. Truss leg and beam leg bridges are commonly called "beadstead" bridges.

Plans and details for Steel Truss Bridges

Plans for Timber Bridges

Plans for Concrete Bridges

Plans and Photographs of Bridges

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