Baltimore & Ohio Railroad, Bollman Bridge, Spanning Potomac River at Harpers Ferry, Harpers Ferry, Jefferson County, WV

Significance: Wendel Bollman's "suspension truss" patented in 1852 was the first iron bridge widely utilized by a railroad. Employing cast iron tension members, it was constructed over virtually every Baltimore and Ohio Railroad river crossing requiring pier to pier spans of less than two hundred feet. Because it appeared in such numbers at an important juncture in civil engineering history, as intuitive gave way to exact engineering and iron was widely being considered as a construction substitute for wood, Bollman's design received much attention. Its success helped usher in the era of iron bridges and the modern period of structural engineering. But success was short-lived. Competing designs required less iron. Unequal weight distribution among diagonal suspension members caused excessive stress that required frequent adjustment. Bollman's truss was obsolete by 1875.
Unprocessed Field note material exists for this structure: FN-22-A
Survey number: HAER WV-36
Building/structure dates: ca. 1868 Initial Construction
Building/structure dates: 1924 Subsequent Work
Building/structure dates: 1936 Demolished