Monocacy River bridge and viaduct

The Monocacy river bridge and viaduct is a 326ft open deck steel girder bridge with two main spans crossing the river and 2 viaduct sections crossing the floodplain, south of Walkersville, Maryland. Originally constructed by the Frederick and Pennsylvania Line Railroad Company (F&PL). Construction began in late 1871, and continued until July 1872 when the railroad opened that year. It was rebuilt by the Pennsylvania railroad prior first in 1900-1905 as an open deck riveted iron plate under girder bridge. In 1915, the bridge was surveyed as part of the Interstate Commerce Commission's ("ICC") effort to establish freight rates for the Parent railroad. In 1927, the Pennsylvania railroad rebuilt the bridge again using deeper and thicker steel girders, but leaving the masonry piers intact. In 1972, the two 85 foot river spans were washed out by Hurricane Agnes. In 1982, the State of Maryland purchased the bridge as part of the railroad line. In 1995, the State rebuilt the river spans and Pier 3 which is located in the middle of the river crossing was completely reconstructed using concrete to replace the original masonry foundations. In 2015, the State performed minor maintenance on the structure and painted some spans. As of 2016, the bridge is in active rail service, operated by the Walkersville Southern RR.HistoryConstructionBollman Iron BridgeThe original bridge was a "Bollman suspension truss". The Monocacy river bridge and viaduct structures were a mixture of wrought iron tension members and cast iron compression members,including other decorative elements, such as Doric styled vertical members and end towers, all cast iron and detailed. In 1872, Bollman's firm, Patapsco Bridge and Iron Works completed the bridge and viaducts with a total length of 326 feet.