ABSTRACT
The paper examines the contributions of Joseph M. Wilson and Henry Pettit of the Pennsylvania Railroad (PRR) to the design of iron truss railroad bridges in the US. Wilson and Pettit developed statically determinate truss forms, connection details, and details of built-up compression members that were widely adopted by other US bridge designers. These contributions are examined in context of specific bridge designs: the 1869 bridge over 30th Street in Philadelphia, Pennsylvania (PA), the 1871 bridge over the Juniata River at Mount Union, PA, the 1874 East Span of the Monongahela River Bridge near Pittsburgh, PA, and the Delaware River Bridge at Trenton, New Jersey. These designs reflected a change in engineering judgment regarding appropriate bridge characteristics and were distinctive within contemporary international design practices.
