Just in front of the tug in Joe Balynas' Flickr Photo you get a good view of the curved member rolled back on the flat foundation member of the Scherzer Rolling Lift Bridge design.
MWRD posted two photos with the comment:
Westward views of the Cass Street and Jefferson Street bridges in Joliet on July 15, 1910. The Chicago Sanitary and Ship Canal (CSSC) was completed in 1900 and at that time it terminated at the Lockport Controlling Works just north of 9th Street in Lockport. It was later extended further downstream to an area where the MWRD built the Lockport Powerhouse and Lock, effectively taking advantage of a nearly 40-foot difference in elevation between the CSSC and the Des Plaines River for hydroelectric power generation. The MWRD also made improvements to the Des Plaines River downstream of the Lockport Powerhouse as part of the Joliet Project, including river channel excavation, embankment improvements and construction of levees and bridges. Seven bridges were constructed by the MWRD for the Joliet Project, including these bridges at Jefferson Street and Cass Street.