1. A method comprising: determining, by at least one processor, probabilities of congestion of respective road segments of a road network using the following equation: P = S historical S free ⁢ ⁢ flow , wherein P is the probability of congestion of a road segment, S historical is a historical speed of the road segment determined using historical data relating to traffic for the road network and S free flow is an expected seed of vehicles on the road segment in free flow traffic conditions; receiving at least a portion of current data relating to traffic for the road network derived from a Global Positioning System (GPS) in one or more mobile devices; calculating, using the current data, a current congestion of a first one of the road segments determined to have a higher probability of congestion and not calculating a current congestion of a second one of the road segments determined to have a lower probability of congestion, wherein the lower probability of congestion or the higher probability of congestion are determined based on an expected speed of vehicles on the particular road segment in free flow traffic conditions; generating data indicative of a visual representation including an indication of the calculated current congestion of the first one of the road segments; and sending the data indicative of a visual representation including the indication of the calculated current congestion to a navigation device.