About
Thomas Mill Covered Bridge crosses Wissahickon Creek at Thomas Mill Road inside Wissahickon Valley Park in Northwest Philadelphia. It is a Howe truss bridge built in 1855, 86.5 ft long and about 18.7 ft wide. The bridge is closed to cars and is used by pedestrians and cyclists on the park's trails.
History
The bridge dates to 1855. The Works Progress Administration renovated it in 1939, and the City of Philadelphia carried out a second renovation in 2000. The bridge was documented by the Historic American Buildings Survey as HABS PA-19, and it was listed on the National Register of Historic Places on December 1, 1980.
Design
A Howe truss combines heavy timber diagonal braces with vertical iron rods. The rods can be tightened with nuts at their ends, which let builders adjust the truss as the timber settled and made the design easier to maintain than an all wood truss.
Visiting
The bridge stands where Thomas Mill Road meets Wissahickon Creek, within the city's Wissahickon Valley Park. It is open only to pedestrian and bicycle traffic, so visitors reach it on foot or by bike along the park's trails rather than by car.
Sources: Thomas Mill Covered Bridge (Wikipedia)
Photo: Jack Boucher, public domain, via Wikimedia Commons.
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