The Bollman Truss Bridge legacy started and ended in Savage, MD, linking the Savage Mill to the mainline Washington Branch Railroad.
The first Bollman Bridge was a 76 foot prototype designed by Wendel Bollman near the "Savage Factory" train station on the Washington Branch railroad in 1850 (see the National Register documents and Baltimore Sun 26 Oct 1850, Sat · Page 1) before the patent was awarded in 1852. This 1850 Bollman Bridge replaced the original 1835 bridge that was lost to flooding in 1847 (see Baltimore Sun 09 Oct 1847, Sat · Page 2).
The current structure, built in 1869 as seen on the name plate on the front of the bridge, is the last known Bollman Truss bridge and resides in Savage crossing the Little Patuxent River between Savage Mill and what used to be the Patuxent Branch rail line of the B&O railroad. The nearby Bollman Bridge Elementary School is named for the famous bridge, designed by Wendel Bollman. This bridge was designated the first national historic Civil Engineering Landmark in 1966 by the American Society of Civil Engineers and in 1972 recognized on the National Register of Historic Places.
Bollman Bridge was at an unknown location somewhere else on the B&O system before it was moved to its current location in 1887 /1888 (depending on the source) when the B&O formally opened the Patuxent Branch line connecting the main Washington Branch line with Savage Factory, and eventually to the Guilford quarries in 1902. The Bollman, and Pratt, truss bridge designs for the B&O allowed the bridges to be portable and once they were no longer structurally sufficient for current use they were often disassembled and moved to other locations, like the Patuxent Branch rail line, that did not require as rugged of a bridge due to lighter rails and engines.
One of the things I can not reconcile is this 1881 newspaper article (see below), which is very specific, about a new truss bridge over the Patuxent between the Savage Mill and the Washington Branch which was 186 feet long, 9 feet wide and 26 feet above the river. These dimensions are within a few feet of the blueprint drawing above. Was the Bollman Bridge placed there in 1881 before the line opened up in 1887? I see different information on different authoritative Websites. It will take a while to untangle them.
Here is a link to the 1971 National Register Form and a link to early photos of the Bollman Bridge from the US Library of Congress. Below is the patent for the original design used in 1850 for the very first iron bridge used by the B&O Rail Road. Please see the discussion in Did You Know? #11 - There were two famous Bollman Bridges near Savage for more details.