For many years, this bridge was shared between the Milwaukee Road and the Omaha Road. In recent years, the crossing has been shared by the Union Pacific and Canadian Pacific railroads, serving part of the traffic that travels along the south side of the Minnesota River to the UP yard in Savage at the south end of the Bloomington Ferry Bridge. Despite a fair number of trains using this crossing, the bridge is maintained in an open position except when trains are using the bridge.
The unusual feature of the swing span is that the pivot point is not in the middle of the bridge. Rather, the river section of the swing span is 185 feet long, while the other side is only 75 feet long. This feature is called an asymmetrical swing bridge, and it is the only bridge like it on the Mississippi River.
According to a local legend, once the bridge was erected, the owner of the land adjacent to the rail line objected to having the bridge swing over his land. To solve the problem, the railroad simply cut off that part of the bridge, and balanced it out with the large concrete slug that hangs off the back end of the swing span. The real reason for the non-symmetrical swing span is that the navigation channel is so close to the shore. The result is that half of the swing span would swing over dry land, so why span that dry land with expensive steel when cheap timber and cheap concrete would do the trick?
The last photo shows a close up of the lettering on the concrete counter-weight. The two railroad names are the C.St.P.M.&O. Ry and the C.M.&St.P. Ry. The C.St.P.M.&O. Ry logo is from the Chicago, Saint Paul, Minneapolis, and Omaha Railway, known as the Omaha Road. Much of the Omaha Road stock was owned by the Chicago Northwestern as early as 1882. The C&NW took over operations of the Omaha Road in 1947, and purchased it outright in 1972. The C&NW itself merged into the Union Pacific Railroad in 1995.
The C.M.&St.P. Ry logo is the famous Milwaukee Road. It used a number of names in its early days, but settled on Chicago, Milwaukee, and Saint Paul Railway in 1874. It reorganized as the Chicago, Milwaukee, Saint Paul, and Pacific Railway in 1927. The Milwaukee Road was plagued by bad management and bad accounting, leading it into bankruptcy several times. The end came in 1986 as the Milwaukee Road was merged into the Soo Line, which itself became part of the Canadian Pacific Railroad. This long chain of owners and mergers explains how it came to be that the UP and CP share this bridge, and why the locals often refer to this bridge as the Omaha Road Bridge.
The photo at the top of the page is a view of the swing span in the open position. It is very apparent in this view that the pivot point is not in the middle of the the moving truss span. In fact, the pivot point is much closer to the end with the counterweight. The photo below shows the deck plate girder section of the bridge.