### Instruction: Why are there speed limits on public roads?
### Response: Governments create and enforce speed limits for humans driving vehicles on public roads in the interest of public safety. The speed limits generally depend on the type of road, including whether it is in a residential area or a freeway. Police officers enforce posted limits by patrolling the roads and checking the speeds of vehicles around them using radar technology. By preventing vehicles from traveling at excessive speeds, speed limits help keep roadways safer for everyone.