Bollman Truss Railroad Bridge

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Bollman Bridge with Savage Mill tower in background, 1970.

The Bollman Truss Railroad Bridge at Savage, Maryland is the sole surviving example of a revolutionary design in the history of American bridge engineering. The 160 foot (48.8 m) double-span truss bridge is one of the oldest standing iron railroad bridges in the United States. It was built for an unknown location on the main line of the Baltimore and Ohio Railroad in 1869, and was moved to its present location, spanning the Little Patuxent River on the spur to the Savage Mill, around 1887. This spur line dates to around 1840 and originally crossed the river on a stone arch bridge; however, due to alterations to the mill in the 1880s and topographical restrictions, a replacement bridge was needed. The bridge remained in service until the mill closed in 1947; switching crews used additional cars in order to avoid crossing the bridge with locomotives, and thus there was never a need for a more substantial structure.

Paired end posts at mid-span showing connection of diagonal tension members with anchor casting, 1970.

The type was named for its inventor, Wendel Bollman, a self-educated Baltimore engineer. It was the first successful all-metal bridge design to be adopted and consistently used on a railroad. The design employs wrought iron tension members and cast iron compression members. It was an improvement over wooden structures, as the independent structural units lessened the possibility of structural failure. Patented on January 6, 1852 (No. 8,624), the company built about a hundred of these bridges through 1873. Their durability and ease of assembly greatly facilitated expansion of American railroads in this period. Bollman's Wells Creek Bridge has also survived, but it employs a different type of truss system.

The bridge was restored by the Howard County Department of Recreation and Parks in 1983, and more recently underwent additional preservation work and was rededicated on September 16, 2000. Today it receives regular maintenance as part of Savage Park. In 1966 it was designated a Historic Civil Engineering Landmark by the American Society of Civil Engineers. The bridge was listed on the National Register of Historic Places on December 18, 1972, and was designated a National Historic Landmark on February 16, 2000.