Navigation devices, services, and methods are provided for determining an average traffic speed for a path segment using probe data from a plurality of navigation devices. The method for determining an average traffic speed may include retrieving probe data from a plurality of navigation devices, each navigation device traveling over at least a portion of a defined path segment for at least a portion of a defined time interval, wherein the probe data for each navigation device comprises an instantaneous velocity of the navigation device. The method may further include calculating a total distance traveled and a total time traveled by the plurality of navigation devices over the path segment and within the time interval using the instantaneous velocities from the retrieved probe data. The average traffic speed may then be determined based on the calculated total distance traveled and total time traveled.