Description:
The Guilford Quarry Pratt Through Truss Bridge was constructed circa 1902 as a single-span wrought-iron, 83-foot-long, five-panel, pin-connected Pratt through truss bridge. The truss is fifteen feet wide to accommodate a single track with a 2-86 ton live load. It is 21 feet high supported with large granite abutments; the end points of the truss rest on the massive granite block abutments, spaced 83’ apart center to center. Atypically, this truss bridge doesn’t cross the river at a right angle as do most truss bridges; it has a 35-degree left-hand skew with inclined end-posts at each end. A skew is not common and provides more engineering difficulty to construct, but it allows a train to cross a river in a straight line if the banks are not perpendicular to the railroad alignment. Pratt bridges are named for Caleb and his son Thomas Wllis Pratt, who patented their design in 1844. The design used wood as the upright compression members and wrought iron as the diagonal tension members which was the opposite of the predecessor Howe truss bridge. However, with the success of the all-metal Bollman bridges, the Pratt truss bridges were eventually made of all wrought iron and became increasingly popular due to their simplicity of design and construction in the field. This pin-connected Pratt through truss was the most common type of railroad through truss of the 1880s and 1890s, covering the transition from wrought iron to steel. After 1900, the pin connections give way to riveted connections, which were more rigid and suited to the heavier construction needed for the ever-increasing live loads of locomotives. Pratt trusses also gave way to Warren trusses, which were more suited to riveted connections. This meant that pre-1900 or so truss bridges on main lines, in particular, became under-performing even though they were barely 20 years old, sometimes less. The B&O, and other railroads, moved some of the pin-connected trusses to branch lines or to overhead (highway) use where they were still adequate. The Guilford Quarry bridge was originally constructed in Ohio in the late 19th century, and it was moved to its current location circa 1902.
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Significance:
The Guilford Quarry Pratt Through Truss Bridge is architecturally significant as a representative surviving example of a Pratt through truss bridge. The use of this bridge, which was moved from its original location in Ohio, provided a means for the granite industry to grow locally, creating a flourishing community around it. The B&O opened the Washington Branch in 1835. The line runs roughly along Howard County’s eastern border, connecting Baltimore with Washington, D.C. In 1888 a fright line was extended from this branch to Savage to reach the mills there, and in 1902 it was extended to reach Guilford, presumably so that granite from the Maryland Granite Company quarry could be more easily transported. The spur crossed the Little Patuxent River immediately south of Guilford, and the bridge was presumably moved from Ohio for this purpose. The Maryland Granite Company was dissolved in 1918 and by 1919 the bridge was no longer in use. By 1928 the portion of the rail line was officially abandoned. The bridge was eventually transformed into a vehicular roadway. Between 1919 and 1930 rights and then formal ownership of the property was transferred to William Handley and his wife Frances, including the bridge. In 1933, Frances Handley, then a widow, sold the land, including the bridge, to Paul and Mary Kesterson, who were allowed right-of-way access to the State Road and to make repairs, jointly with others, to the bridge as needed. The property was sold again to Dennis Gaither in 1950. By the 1970s, the development of Columbia and the nearby construction of the new Route 32 and I-95 left the bridge unused and neglected. The bridge was restored in 2002 with a new deck connecting the pathways between Lake Elkhorn and Savage Park, and is now a pedestrian bridge maintained by the county.
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