Methods and devices for using position logs of vehicles to determine the presence and behavior of traffic controls are disclosed. An example method includes receiving movement data that is indicative of movement of a plurality of vehicles through an intersection. The movement data may be received by a computing device and may include, for each respective vehicle, data indicative of the respective vehicle's position as a function of time for multiple instances of time. The method may further include detecting a pattern in the movement data using the computing device. The detected pattern may be indicative of a probable traffic control for the intersection. According to the method, an indication of the probable traffic control for the intersection may be stored in a database.