necessitating the use of caissons, with air chambers, in which the men, engaged in removing the debris in order to reach bed-rock, have worked under a pressure of . The bridge consisted of the following segments: a western approach viaduct, four Whipple deck truss spans, a through truss span over the western navigation channel, a deck truss span, a viaduct over Garrett Island, one and one Whipple deck truss spans, a through truss span over the eastern navigation channel, and finally a eastern approach viaduct. The eastern approach also crossed the PRR's Columbia and Port Deposit Railroad. Unlike the remainder of the Philadelphia line, the bridge contained only a single track. The bridge cost $1.7 million to construct. It was opened with a ceremonial train on May 11, 1886. Freight operations began on May 25 of that year; passenger operations followed on August 23. The first Washington to New York train to use the new route crossed on December 15. Starting in 1890, passenger trains that used the bridge were marketed under the name Royal Blue Line. 1908-present: Second B&O Bridge In the early years of the 20th century, the iron bridges on the Philadelphia line could no longer handle the latest locomotive designs at optimal speeds. The Susquehanna Bridge also required an additional track. In November 1907, the American Bridge Company and Eyre-Shoemaker Company began renovating the structure. Timber falsework was used to shore up sections of the bridge under construction, allowing construction to proceed with minimal disruption to traffic. On September 23, 1908, a coal car derailed on the bridge and struck a mobile crane. The crane collapsed, bringing down the eastern channel through truss, which sank in deep water. One person was injured and 12 cars at the end of the train were lost. The PRR granted the B&O the right to detour trains over its new double-track bridge, and so track connections between the B&O and PRR were built at Swan Creek (west of Havre de Grace) and Aiken (near Perryville). At Aiken, the steep grade between the two lines required the use of helpers. This detour was maintained while the renovations to the Susquehanna Bridge were completed. Compared to the original bridge, the new bridge has shorter and more numerous deck truss spans. The superstructure is constructed of of steel and can support two tracks. Pennsylvania through truss spans are used over both navigation channels.