Bridge Description McConnells Mill Covered Bridge, Ellwood City Pennsylvania
As finished, the 90'-0"-long "Bridge at Kennedy's Mill," as it was referred to in court records, featured a Howe truss based upon a variation of the 1846 patent with pairs of wrought iron vertical rods extending from the counterpoint of the diagonals. Each panel contains two 6" by 7" diagonals leaning toward midspan, and one diagonal leaning away, bolted together where they cross. The diagonal members have square ends that rest on wooden impost blocks, and are held in place by tension in the vertical rods. Metal plates at each end of the rods help distribute forces to the top and bottom chords. The bridge's floor system sits atop the bottom chords.
The top chords are comprised of three wooden beams running longitudinally and bolted together at intervals. In turn, these support the gabled roof which consists of rafters supporting the longitudinal wooden roof planks. A horizontal Howe truss, in the plane of the top chord, forms the lateral sway bracing. Here, cast-iron impost blocks receive the ends of the diagonal members. The vertical clearance between this truss and the wooden deck is 12'-7". The roof is protected by asphalt paper tacked into the wooden roof planks.
The 14'-0"-wide wooden deck consists of 2"-thick transverse planks ofvarying widths crossed by plank runners on either side. Where the decking meets the truss, a 6" x 6" wheel guard runs the length of the bridge. The end posts on each end of the bridge are comprised of three wooden beams side by side, separated by two vertical wrought-iron rods. The bridge has an underclearance of 20'-6" at mid-span. The 14'-0"-wide approaches curve sharply onto the bridge on both ends.
As was common with the covered bridges of western Pennsylvania, McConnelPs Mill Bridge features vertical board-and-batten siding. The siding covers both sides, except for a l'-0"- high "window" under the top chords, permitting some light to enter the otherwise dark interior. The board-and-batten siding also wraps around a few feet onto either end of the bridge, covering the vertical end posts and gables. This portion of the board-and-batten rests on the masonry abutments, where rough-cut stones jut out from under and around it.
The original deck support, however, is no longer in place. In the late 1950s, the state replaced the decaying wooden floor system, except for the bottom chords. A new steel floor system replaced the original wooden stringers, wooden floor beams, and wooden sway bracing. The state added supplemental steel girders - large wide-flange I-beams - beneath the bottom chord on either side. A new wooden deck was also added during this rehabilitation, and around this time the original roof covering was replaced with a green asphalt roll roofing. It may have also been around this time that the bridge's board-and-batten siding was painted red; it had previously been white. This rehabilitation occurred sometime after 5 October 1957, when the bridge and the mill together became a part of McConnell's Mill State Park. The mill and the dam were reconstructed in 1963, and the mill is now a museum.
Underneath the eastern edge of the bridge are rectangular grooves in a line chiseled out of some of the creek's rocks, suggesting that a trestle bent may have supported the previous bridge on this she. Under the western edge are eight square holes in a roughly semicircular slab of stone below the western abutment. These holes and the semicircular rock are plainly visible in a sketch of the bridge and the mill drawn by R. Caughey of "Forest Mills, McConnell, Wilson, & Co., Proprietors" between 1875 and 1879. The holes may have supported part of the previous bridge at the site, although documented explanation of these holes or the rectangular grooves on the opposite side has yet been discovered.
In 1978, a bridge inspection undertaken by Frank B. Taylor Engineering Company of New Castle, Pennsylvania, reported the bridge in good condition overall, recommending only that bridge inspections be stepped up to every two years and that signage indicating a weight limit of five tons and a clearance of 10'-0" be posted. The study also noted that the bridge was covered in graffiti. Another study by the same company in 1995 recommended replacement of the wooden decking and other rotted wooden components, replacement of the roof, and a thorough re-painting. Unless one climbs under the bridge, only the steel I-beams, currently painted blue, are visible from the exterior.
These repairs are the only major alterations to the bridge. The added steel has kept the bridge working under heavier loads; the Howe truss performs considerably less of the support work than it did in the past. Yet the truss is largely intact, a reminder of nineteenth-century technology. Carved into the diagonal members and the interior of the board-and-batten exterior are years of graffiti, dating as far back as 1905, and probably earlier.