Wanted: Illinois & Michigan Canal Workers
Information for Bridge
Builders
Bridges. When opened in 1848, there were 25 bridges crossing the canal, each at a minimum height of 11.6 feet above the water. All were of the "Howe" truss type and had spans of 70 feet and upwards. In the Howe truss all the vertical members of the bridge are in tension while the inclined members are in compression. The vertical members were usually iron or steel rods while the inclined members (as well as the upper and lower chords of the bridge) were made of timber.
(The truss seen at the railroad bridge crossing the canal in Utica is of the "Pony" type. This is a truss low in height, spanning distances of between 30 and 80 feet.)
At one time or another at least four different bridges crossed the canal at Chestnut. In 1876 there was a swing bridge, in 1891 a 115-foot long draw bridge, in 1907 an iron swing bridge, and in 1930 a hand-operated swing bridge constructed at cost of $23,440.
The Walnut Street bridge of the "Chicago, Burlington and Quincy Railroad" has seen at least two types: A drawbridge in 1891 and an iron swing bridge in 1907.
Both LaSalle and Columbus streets have had at least three different bridges. At LaSalle Street there was a wooden draw bridge in 1891, an iron swing bridge in 1907, and the present concrete bridge. At Columbus Street there was a turn bridge in 1876, a drawbridge in 1891 and 1907, and the present concrete bridge.
(Vierling 1986, 52)
Return to Wanted: Illinois & Michigan Canal Workers Lesson Plan