Some police departments have strict policies governing when an officer shall write a fine for a violation and when a written warning is permissible. Most departments permit their officers to use their discretion. In the case of speeding, many factors are taken into account. The speed at which the vehicle is traveling, width of the street, population density, and the presence of special hazards, i.e. children in the area, play grounds, blind driveways, etc. Speeds greater than 10 m.p.h. over the speed limit on a street usually results in a fine being written.