Car parks and parking lots can be dangerous to drivers and their passengers. Some are not (or poorly) lit at night. Persons intent on mischief or criminal activity can operate without being seen. Large parks and lots attract both male and female prostitutes who, if turned away, may retaliate in some way such as "keying" a vehicle. Other hazards in urban lots are rusty nails on the pavement, broken glass, and vermin such as rats. 