Covered bridges played an important role in early America. At the beginning of the nineteenth century, when covered bridges became widely used, only three alternatives existed for spanning a creek or river: the arched stone bridge, a solid timber bridge, and a covered bridge. The arched stone bridge required no roof because the road deck was arched to drain to each end of the bridge, but was very expensive to build and limited in span.
The solid timber bridge, which was limited in span to the length of a single heavy timber beam, had no roof because it relied on the size of timbers to resist rot for the short service life of the structure. For a simple timber-beam bridge, wide crossings could only be achieved by building piers in the riverbed.
The innovative solution, which flourished during the first half of the 19th century, was the covered bridge. Covered bridges are heavy-timber structures comprised of a pair of trusses built into the sidewalls of the bridge, which support a floor between the trusses, and are protected by wall siding and a roof. Utilizing truss technology that was widely used for barns and churches, local timber framers could build long trusses using local timbers and local tradesmen. Side walls and roofs were added to the trusses to protect the timbers from the weather. It is claimed that during the winter, snow was shoveled on to the bridge flooring to allow sleighs to pass over the bridge. Covered bridges were largely replaced with iron bridges during the second half of the 19th century, but a small number have survived, including two in the Laurels Preserve.
MARY ANN PYLE AND HAYES CLARK BRIDGES IN THE LAURELS
The Mary Ann Pyle Bridge, which is listed on the National Register of Historic Places, is the older of the two bridges at The Laurels Preserve, and is better preserved. The Hayes Clark bridge was largely rebuilt during the 1970s, at which time the original trusses were converted to simple-span beams by the stone pier that was built in the stream at mid-span.
This project was precipitated by a decided drop in the southwest corner of the Mary Ann Pyle Bridge in 2006, which was temporarily repaired by means of a heavy steel “cradle” that replaced the rotted end of the bottom chord of the west truss where it bears on the stone abutments. From casual observation of other bridge components, it was evident that
timber deterioration was not limited to the one failed member. Team Structural Engineer, Keast& Hood Company, conducted an examination and non-destructive testing program for both bridges. Using resistance drilling and a resistograph, engineers were able to determine the internal condition and structural capacity of existing timber
members. The design team, led by Frens and Frens, LLC, Restoration Architects, assessed all aspects of the
bridges and prepared drawings and detailed specifications for restoration of both bridges.
Through a competitive bidding process, Frank Stroik Historical Restorations and William H. Shainline were selected as timber framers and restoration carpenters to restore the two bridges. Given the significance of the two bridges and their sensitive environmental settings, the work will be completed with the highest levels of craftsmanship and experience.
The solid timber bridge, which was limited in span to the length of a single heavy timber beam, had no roof because it relied on the size of timbers to resist rot for the short service life of the structure. For a simple timber-beam bridge, wide crossings could only be achieved by building piers in the riverbed.
The innovative solution, which flourished during the first half of the 19th century, was the covered bridge. Covered bridges are heavy-timber structures comprised of a pair of trusses built into the sidewalls of the bridge, which support a floor between the trusses, and are protected by wall siding and a roof. Utilizing truss technology that was widely used for barns and churches, local timber framers could build long trusses using local timbers and local tradesmen. Side walls and roofs were added to the trusses to protect the timbers from the weather. It is claimed that during the winter, snow was shoveled on to the bridge flooring to allow sleighs to pass over the bridge. Covered bridges were largely replaced with iron bridges during the second half of the 19th century, but a small number have survived, including two in the Laurels Preserve.
MARY ANN PYLE AND HAYES CLARK BRIDGES IN THE LAURELS
The Mary Ann Pyle Bridge, which is listed on the National Register of Historic Places, is the older of the two bridges at The Laurels Preserve, and is better preserved. The Hayes Clark bridge was largely rebuilt during the 1970s, at which time the original trusses were converted to simple-span beams by the stone pier that was built in the stream at mid-span.
This project was precipitated by a decided drop in the southwest corner of the Mary Ann Pyle Bridge in 2006, which was temporarily repaired by means of a heavy steel “cradle” that replaced the rotted end of the bottom chord of the west truss where it bears on the stone abutments. From casual observation of other bridge components, it was evident that
timber deterioration was not limited to the one failed member. Team Structural Engineer, Keast& Hood Company, conducted an examination and non-destructive testing program for both bridges. Using resistance drilling and a resistograph, engineers were able to determine the internal condition and structural capacity of existing timber
members. The design team, led by Frens and Frens, LLC, Restoration Architects, assessed all aspects of the
bridges and prepared drawings and detailed specifications for restoration of both bridges.
Through a competitive bidding process, Frank Stroik Historical Restorations and William H. Shainline were selected as timber framers and restoration carpenters to restore the two bridges. Given the significance of the two bridges and their sensitive environmental settings, the work will be completed with the highest levels of craftsmanship and experience.