City Police cars will sit on the corners of Chicago St. and/or Hydrolic St. by the Larkin Bldg. Exchange St. is a straight run and its easy to go above the speed limit of 30 mph. They hide on the side and you cannot see them until you are right on top of them , but they can see you coming well in advance to know if you are speeding or not. Its best to just do the speed limit at least one block or more from these intersections just to make sure they are not there. I have seen them there 3 out of 5 days a week , just sitting and watching traffic. Be careful.