Disclosed is a methodology for the collection, processing and distribution of traffic data and delivering more accurate routing in GPS-based Personal Navigation Assistants (PNAs). The methodology includes a) Data Collection Methodology (DCM), b) a Data Incorporation Methodology (DIM), and c) a Routing Methodology (RM). The DCM regards the collection of information related to the traffic flow in each road. The DIM includes a procedure executed at a central system (CS), outside the PNA, performing the incorporation of the “trace data” (i.e. user-submitted route-related information, including a list of periodically collected, time-stamped GPS samples, augmented with other parameter values defining the vehicle-type, weather-conditions, road-type, holiday-type), collected by the DCM. The RM determines, by means of suitable PNA software, the shortest route from a starting point to a final destination, through the combining the static data from existing maps residing inside the PNA, with the dynamic (time-variant) data derived by the DIM.