Laughery Creek Triple-intersection Pratt Truss
This is an image set within the Bridgemeister collection.
| Bridge: | Laughery Creek Triple-intersection Pratt Truss |
| Location: | Aurora vicinity, Indiana, USA - Laughery Creek |
| Coordinates: | 39.024611 N 84.885917 W |
| Maps: | Acme, GeoHack, Google, OpenStreetMap |
| Image Set Contributor: | James Adorno |
| Related Image Lists: | All from James Adorno All in Indiana All in USA All Truss Bridges |
| Credit: | All photos by James Adorno and Desi Krell. Please do not reuse without permission. |
Built in 1878, this is probably the only surviving triple-intersection Pratt truss. In Great American Bridges And Dams, Donald C. Jackson explains: "... is a rare example of a triple-intersection Pratt truss, a variation on the double-intersection form. To build economical long-span, simply supported truss bridges, it is advantageous to design very tall structures. The amount of material required for a given span length thus can be reduced substantially over a shallower truss of equal length. When using Pratt trusses, engineers quickly realized that single-intersection designs (i.e. those in which the diagonal tension members extend the length of only one panel) could not be used for very tall structures unless the panel length was quite large... This led to the development in the late 1840s of the double-intersection Pratt truss by Squire Whipple (1804-88) in which the diagonal tension members extended across two panels... in a few instances, its success prompted construction of triple-intersection Pratt trusses... The triple intersection Pratt truss never became popular because its extremely long diagonals were not particularly rigid, especially under heavy, fast moving loads."
