In Cook County, a traffic violation can be judged as a petty offense, misdemeanor, or felony, punishable by the following degrees of sentencing: (chicagolawyer.com)
If on private land you are trespassing and engaged in de minimis damaging of signs since some effort goes into placing them and are probably guilty of a petty offense or two of criminal mischief and trespassing. (law.stackexchange.com)
The government only requires courts to allow trials by jury when it is not a petty offense. (law.stackexchange.com)