Navigation system

A navigation guidance system comprising: means (49) for storing data defining a road network within a geographical area; means (51) for storing data defining speed and time characteristics for roads of the road network, wherein said speed and time characteristics define traffic speeds along the roads in the network at different times; means (41) for receiving data from a user defining a travel plan that includes a place of origin, destination and a location plan proposed travel; and means (47) for route determination, comprising: (i) means (47) for determining traffic speeds for the roads of the road network at the proposed travel time using said data defining said characteristics speed and time; and (ii) means (47) to calculate the fastest route from the town of origin to the destination location defined in the travel plan to the proposed travel time using data defining the road network and traffic speeds for certain roads in the road network.