Route planning system, route planning method and traffic information update method

The invention discloses a route planning system, a route planning method and a traffic information update method. A route planning system includes a network server. The network server includes a plurality of road section data, in which each road section data includes a distance and a plurality of average speed rate data corresponding to a plurality of time intervals. The route planning system calculates at least one possible route according to a departure time, a departure point, and a destination point. The possible route includes a plurality of possible road sections from the departure point to the destination point. The route planning system dynamically searches the average speed rate data of the estimated passing time intervals according to the possible road sections and the distances respectively to calculate the travel time of each possible road section and adds them to receive a total travel time of the possible route.