Wendel Bollman - Bridge Designs

Bridge Designs

Bollman began working on a new truss configuration for iron bridges, and in 1849 Latrobe found it acceptable for use on two of the B&O's shorter spans. In 1851 Bollman replaced the 124-foot (37.8 m) wooden bridge at Harpers Ferry. This would become his most famous bridge and was rebuilt many times using his system during the American Civil War (it came under frequent enemy fire). Bollman used the idea of redundancy of members so that his truss systems did not fail. Although abstract theory was often used to design bridges during this time period, Bollman used math and modeling instead.

On January 6, 1852, Bollman was awarded patent No. 8,624 for his unique design known as the "Bollman truss." He left the B&O and founded W. Bollman and Company in 1858 with his partners John Clark and John H. Tegmeyer. The B&O continued to contract with him for bridge design. Not all his designs used the Bollman truss. W. Bollman and Company dissolved about 1863, but two years later Bollman founded Patapsco Bridge and Iron Works which lasted until his death in 1884. His companies built bridges in Cuba, Mexico, and Chile, as well as the eastern United States.

Although far more durable than the wooden bridges they replaced, most of Bollman's bridges have not survived. This is due to changes in railroad equipment, rather than their construction. New technologies for making inexpensive steel in the late 19th century made its use in railroad bridges practical. Steel bridges could carry heavier locomotives and soon wrought and cast iron bridges became obsolete; the iron was easily recycled. The Savage bridge survives because it was on an industrial spur for a mill that closed in 1947. The Meyersdale bridge was moved and converted into a road bridge around 1910. The Harpers Ferry Bridge was destroyed in a flood in March 1936.

Bollman is important not only because he was perhaps the most successful of the latter (self taught engineers) class, but because he was probably also the last. He may be said to be a true representative of the transitional period between intuitive and exact engineering. —Frank Griggs, Jr.