Commerce has just recently begun heavy speed enforcement on a 3.5 mile stretch of I-85, which is now considered to fall within their city limits. I have seen them sitting in the median just before where the city limit signs are if you are coming from either direction (usually at night). This cannot be legal because the "speed checked by detection devices" sign is slightly further down the road, and, if I am correct, the police must be at least 500 feet past this sign before they can record speed.