The bridge did have a close call in March 2004, when a large hemlock tree fell on the roof during a storm. Luckily, in 1957 engineers added concrete beams under the bridge which prevented it from collapsing into the creek. It was repaired the following September.
This is one of four Howe Truss bridges still standing statewide and this one located at the Mill has the longest span of them all. Most bridges in Pennsylvania use a Burr Truss. The Howe Truss was patented in 1840 by William Howe, with an extended patent in 1850. The design consists of a series of diagonal beams and uses steel rods for additional support. The Howe Truss was initially used for railroad bridges due to its strength.
In the 1950s many covered bridges were being replaced by modern versions. It is fortunate that this one was not. Not far from here, Breakneck Bridge was also built in 1874 originally as a covered bridge. It was replaced in 1952 with a concrete one after a coal truck fell through the floor.
More info and sources:
- PA Department of Conservation and Natural Resources Website
- Wikipedia - Howe truss
- Wikipedia - McConnells Mill Bridge
- Pittsburgh Post-Gazette, 'A troubled bridge'
- Pittsburgh Post-Gazette, 'Got it covered'
- National Register Historic Places
- National Register of Historic Places Inventory/Nomination: McConnell's Mill Covered Bridge (pdf)