Joseph Chaley

Who was Joseph Chaley?

Joseph Chaley was a French civil engineer and a pioneer designer of suspension bridges in the 19th century. He was a medical officer in the army before becoming a bridge designer.

Chaley pioneered the construction of suspension bridge cables by bringing together individual wire strands in mid-air, a technique later known as aerial spinning. Previously, the entire cable had been bound together before lifting into place, but Chaley's system, inspired by the ideas of Louis Vicat, allowed considerably longer cables to be erected at less cost.

He built the Grand Pont Suspendu at Fribourg in 1834, a world record-breaking span of 273m, only overtaken 16 years later by Charles Ellet Jr.'s 308m span Wheeling Suspension Bridge. Chaley had previously worked with Marc Seguin's brother Jules on the Tarascon-Beaucaire Bridge and also the Chazey-sur-Ain Bridge.

Chaley first presented a proposal for the Grand Pont Suspendu in February 1830, and was awarded the contract in June of that year. His estimated cost of less than 300,000 florins was well below other competitors, including Guillaume Henri Dufour.