FAIRMOUNT SUSPENSION BRIDGE

摘要

On January 1, 1842, the three Philadelphia County Commissioners celebrated a grand opening of their new suspension bridge over the Schuylkill River just outside city limits at Fairmount. The toll-free two-lane highway crossing was the first of its kind in North America. Philadelphians celebrate the first day of each year, Mummers Day, as a traditional major holiday, which may have added some sort of festive air to the event, although the suspension bridge preceded the now-famous parades by several decades. Fairmount Suspension Bridge was one of the most significant bridges ever built in the USA for several reasons. It was a public structure, as opposed to a private enterprise, and therefore it occupied an important place in our civil engineering history among the forerunners of thousands of state and county highway structures all over the continent. It was built using innovative design theory and construction techniques taught at the world's foremost engineering school in an era when academic bridge building concepts were almost unknown in this country. Most importantly, it was a great success, stimulating dozens of other designers and builders, with the result that wire cable suspension bridges became the norm, chain cable suspension bridges soon were phased out, and design leadership in long span bridges was passed from Europe to America. (Figures 1 & 2) Ironically, despite the great political and engineering significance of the 1842 Fairmount Suspension Bridge, and its 33-year record of reliable service, no marker of any kind identifies the location at this time. The purpose of this essay is to illuminate the obscure history of this remarkable structure, traditionally known to Philadelphians as The Wire Bridge, correcting a few distortions and misunderstandings that have crept into the historical record during the 20th century.