A method for constructing and revising road maps in a vehicle map database using vehicle location signals to provide traffic flow information for recognized vehicle patterns from past vehicle travel. The method includes identifying vehicle travel segments as a series of exemplar points from the location signals. Exemplar points in each travel segment are eliminated to define the travel segment by a beginning exemplar point and an ending exemplar point. A potential ending exemplar point may be redefined if an average location of the exemplar points from a line connecting the beginning point and the potential ending point is outside of a threshold distance. The travel segments are stored in a database, where each stored travel segment includes a travel time. The method compares new vehicle travel segments to the stored vehicle travel segments to identify a match, and then revise the vehicle travel time for the stored travel segments.