The upper chord of the through trusses were a single cast-iron tube, large enough that it would "permit the passage of a small man through from end to end". The end posts were Keystone columns with wrought-iron heads and feet.
The floor beams are 12 inch channel, sandwich with and forming part of the lower chord. The ties are attached directly to these floor beams without any lengthwise stringers.
1868. Construction started in August.
1871. Bridge opens May 29th and is the second railroad bridge to span the Missouri River (after the 1869 Hannibal Bridge in Kansas City).
1879. Nov. 8, the west trellis span of the bridge gave way while an eastbound livestock train was crossing the bridge. Eighteen cars fell into the river and three men were killed and 4 injured. The railroad concluded it was caused by derailment. The coroner's report pointed out lack of maintenance as indicated by the rotting deck planks.
1880. Western trellis truss replaced
1881. Dec 8, a westbound livestock and freight train enters the east span. It collapses with the engine on it. 18 cattle and 13 freight cars join the engine in the river. The engineer was the only fatality. The railroad again claimed it was caused by derailment. Critics blame poor design.
1882. Other two trellis trusses replaced.
1883,1884. The Fink deck truss spans are replaced with Whipple through truss spans and the girder approach spans are replaced. No cast iron was used in any of the 1880-1884 upgrade.
By 1884, virtually the entire bridge superstructure had been replaced and upgraded. See https://bridgehunter.com/mo/st-charles/first-wabash-rr/ for info on the upgraded bridge.
Sources include: Missouri Railroad and Warehouse Commission, Annual Report 1884 Railroad Gazette, Volume 3, January 1, 1871