Rocky Ridge vicinity>
Old Mill Road Bridge, Spanning Owens Creek on Old Mill Road, Rocky Ridge, Frederick County, MD
Photo Caption Pages
Spanning Owens Creek on Old Mill Road, Rocky Ridge vicinity, MD
Find maps of Rocky Ridge, MD
Documentation compiled after 1968.
Survey number HAER MD-36
Building/structure dates: 1882 initial construction
National Register Number: 79001131
Significance: This is a well preserved example of a Pratt Through Truss bridge with pin connections. As of 1983, it is the only bridge known to survive in the United States that can be directly attributed to the Pittsburgh Bridge Company. Though built in the standard Pratt configuration (vertical compression members, diagonal diagonal tension members) the Old Mill Road Bridge is distinguished by its use of riveted floor beams rather than rolled floor beams. In line with the bridge's name there are the ruins of a mill located approximately 75 yards west of the structure. Almost certainly the bridge was built to provide access to the mill. It is also likely that the present bridge was not the first built on the site. The Old Mill Road Bridge is listed on the National Register of Historic Places.
Pittsburg Bridge Company
Historic American Engineering Record (Library of Congress)
1. GENERAL VIEW LOOKING NORTHEAST SHOWING THE TOPOGRAPHICAL SETTlNG OF THE BRIDGE. THE RUINS OF A MILL ARE LOCATED TO THE RIGHT EDGE OF THE PHOTO. 2. 'BARREL SHOT' OF BRIDGE LOOKING EAST.
3. GENERAL VIEW SHOWING SOUTH ELEVATION OF THE BRIDGE.
4. DETAIL VIEW SHOWING BOTTOM CHORD CONNCTIONS AND 'CAMBER' (OR SLIGHT ARCH) OF THE BOTTOM CHORD.
5. DETAIL, VIEW OF PORTAL BRACING.
6. DETAIL VIEW OF DATEPLATE SHOWING NAME OF FABRICATOR (PITTSBURG BRIDGE COMPANY) AND THE FREDERICK COMMISSIONERS IN OFFICE IN 1882.
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