The Brandon Road bridge will be closed until Oct. 5 after being shut down Monday for more repairs of the center lock mechanism.
The drawbridge over the Des Plaines River has been closed repeatedly for center lock problems and had just been reopened Sept. 7 after being shut down for two weeks for repairs.
The Illinois Department of Transportation now plans to replace the entire center lock mechanism sometime next year, spokesman Guy Tridgell said Tuesday.
In the meantime, IDOT will replace the motor that broke down Monday.
"There continue to be issues with motors on the center lock mechanism failing," Tridgell said in an email. "We presume some of this is related to the age of the bridge, which was built in the 1930s and underwent its last extensive rehabilitation in the 1980s."
He said IDOT has to fabricate or refurbish motors for the center lock "which could be creating issues with compatibility."
The center lock mechanism is used to hold the two ends of the bridge together and is activated whenever the bridge goes up or down to let barge traffic through.