Denver & Rio Grande Western Railroad, Provo River Bridge, Spanning Provo River, Orem Vicinity, Orem

Source document Quoted word for word from HAER UTAH,25-OLMS,1-. Not written, edited or summarised by this site.

T. Allan Comp, HAER THE DENVER, RIO GRANDE AND WESTERN RAILROAD U^l. THROUGH TRUSS IRON BRIDGE: "Ot-M'^ Railroad bridge development has a long and complex history perhaps best summarized by Carl W. Condit in his American Building Art: The Nineteenth Century (New York: ^"' The first "scientifically" designed truss was done ; ,.y ^v .? in wood by Thomas Pratt of Boston in and the first \ "3* v., ' *, - i!' "' ':< " ~ ;-^ i' ,^' iron railroad bridge was completed three years later. By the first true eye bar construction was in use followed in by the first pin-connected truss in which all structural members were made of wrought iron.

Since the use of cast iron in railway bridges ended about it ^raay be assumed that the Denver, Rio Grande and Western Railroad span is of all wrought iron construction, although the survey team did not attempt to determine if any cast iron was used in the structure. The bridge is the popular Pratt design -in- section and employs eye bars^ and pin con- nections at major points. The bridge surveyed was originally one of three spans built in by the Union Bridge Company of Athens, Pennsylvania. Each of the spans was feet in length and the three were designed to carry a narrow gauge rail- road across the Green River in Utah. No original plans or photographs of the bridge as constructed in were m -2- wm encountered in research.

Sixteen years later the railroad |^iverted to standard gauge and dismantled the three-span Green River bridge. The railroad then engaged the Louis- ville Bridge and Iron Company to shorten the dismantled spans to 82 feet and widen each to accommodate standard gauge tracks. One of these modified trusses was installed across the Price River near Wellington, Utah in and then moved again in to its present site across the Provo River at the mouth of Provo Canyon where it replaced an 85 foot wooden Howe truss. A letter from the railroad company indicates this line was abandoned in the land is now owned by the Utah Highway Department.

^ AW' As surveyed, the bridge is an all-metal Pratt.truss, through truss- supported at the level of the bottom chord J/^ and in which the end posts are in compression and all posts , serve as important bearing members. The bridge is fabri- cated from riveted iron plates and is a pin-connected structure generally recognized as the standard American practice of the To allow for expansion and contrac- tion, one end of the bridge is fixed while the other rests on a roller bearing nest. Wooden railroad ties are placed directly in the iron stringers.

Originally constructed in the same year as the 720 foot Lindenthal twin lenticular steel through truss bridge over the tMonongahela in Pittsburgh, and at a time when -3 structural steel was coming into general use for railroad idges, the Denver, Rio Grande and Western Railroad iron bridge cannot be taken as a major essay or innovation in bridge construction. It should be noted, however, that as it now exists on its third site and only half its original length, the bridge can be viewed as a testament to the adaptability and flexibility of American railroad bridge engineering during the last quarter of the nineteenth century. Allan Comp Project Historian August

Bibliography

Condit, Carl W. American Building Art: The Nineteenth Century. (New York: The Denver and Rio Grande Western Railroad Company: Letter from E. H, Waring, Chief Engineer, July 15, File: 8, to Burtch W. Beall, Project Supervisor, Historic American Engineering Record, Utah Survey. Edwards, Llewellyn Nathaniel. A Record of History and Evolution of Early American Bridges. (Orono, Maine: