Wednesday, June 7, 2017

BNSF/CB&Q/B&MR Bridge over Missouri River at Plattsmouth, NE

(1903 Bridge Hunter, 2013 Bridge Hunter, no Historic Bridges, Satellite)

The Burlington and Missouri River (B&MR), which was acquired by the CB&Q in 1872, built the original bridge in 1870. The 1903 bridge was rebuilt in 1976. A photo in a Facebook posting brought these bridges to my attention. The posting explains that the new bridge handles loaded trains and the old one handles empties. The 1903 Bridge Hunter posting has a lot of photos of the new one as well as of the old one since they are next to each other.

I like this view because the man standing on the girder part on the Nebraska side shows the scale of the bridge. The length of the through-truss span over the navigation channel for both bridges is 400 feet.
Post Card View
Many of the pictures capture the differences in bridge construction techniques. Both use a macho through truss to span the navigation channel, The truss for the new bridge is deeper while the cord members are smaller, probably because modern steel is stronger. The new bridge does not use any V-lattice. For the other spans over the river and the flood plain, the old one uses deck trusses whereas the new one uses four steel girders. That photo also shows that the old bridge uses cut-stone piers while the new one uses reinforced concrete. (Reinforced concrete was still being developed as a construction material in the early 1900s.) In that photo we can also see that pin connected tie bars are still used for some of the bottom cords even though the bridge was rebuilt in 1976. This photo shows that for the short spans on Nebraska's river bluff side. the old bridge uses steel girders whereas the new one uses concrete girders.

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