Commercial / Hillside is a connector side street between Route 83 and Wood Dale Roads. The speed limit is 20 (if you can believe it) and it is enforced. The police usually park in the business parking lot just East of Wood Dale Road. They can also be down any side street. Wood Dale Police have been told to catch all speeders in Wood Dale, to make the streets safer but really it is for revenue.
They really enforce it during the school year.