Tomorrow marks 95 years of service for Chicago’s Franklin Street Bridge! Opened on October 23, 1920, this trunnion bascule bridge connects Franklin and Orleans Streets at an angle on the north shore of the main branch of the Chicago River. The bridge uses a pony truss superstructure that features supporting members both below and above deck and extends the top chord of the truss above deck to achieve graceful rounded lines over the entire span.
The bridge was designed to help alleviate heavy traffic on other nearby river crossings and was raised regularly during the mid-20th century for large commercial river vessels. Today, the bridge carries around 17,000 vehicles per day and is raised about 40 times a year, mostly for the seasonal sail boat runs between Lake Michigan and boat storage yards on the South Branch of the river.
You can learn more about the history of the Franklin Street Bridge and Chicago’s 18 moveable “Loop” bridges (all of which are steel!) at www.chicagoloopbridges.com.