Existing comment:
Bowstring Arch Bridge (4)
Originally spanning Big Pipe Creek in Detour, Carroll County, Maryland, this Bowstring Arch Truss Bridge, circa 1872, was reduced in width and moved to its present site over Little Hunting Creek. Patented in the early 1840s by internationally known inventor Squire Whipple, the truss bridge was important to the industry and economics of young America. Borrowing their form from earlier wooden structures, the double iron was less susceptible to damage and wear from the elements. The prefabricated bridges were erected across rural America and many still span waterways.
Truss bridges depend on compression and tension for support against the forces of gravity. The arch itself is under compression and tends to be pushed together by forces acting on it. The thinner diagonal and vertical braces are subject to tension and help support the deck and arch of the bridge. |