Method for creating synthetic data itinerary maps for a centralized server having access to road map data for calculating itineraries in relation to at least one given geographical area, comprising steps of: - receiving, by way of a data exchange module of a centralized server, the data of at least one starting point and a destination point for an itinerary to be calculated; - calculating, by way of an itinerary calculation module, at least one itinerary between a starting point and an arrival point; - identifying, using a manoeuvre detection module, the manoeuvres along the itinerary; - verifying, for each of the manoeuvres, using a module for testing data specifying a direction to be followed, whether a specification of a direction to be followed is available in the available road map data; - if a specification of a direction to be followed is available in the road map data, extracting, using a data synthesis module, the data specifying a direction to be followed; - if a specification of a direction to be followed is not available in the road map data, generating, using a data synthesis module, from the road map data, geometrical indications of road sections to be travelled, said indications being based on the effective geometry of the sections of the itinerary portion in question; - generating, using a synthetic map generation module, an itinerary map including, in the order in which the manoeuvres of the itinerary are followed: - for the itinerary portions for which a direction indication is available in the road map data, the extracted data specifying a direction to be followed, provided on their own; - for the itinerary portions for which a specification of a direction to be followed is not available in the road map data, the supplied geometrical indications of sections to be travelled; - transmitting, using a data exchange module, the data of the established synthetic itinerary to at least one mobile navigation device; - supplying, to a user of the mobile navigation device, the data of the synthetic itinerary received from the itinerary server. - receiving, by way of a data exchange module of a centralized server, the data of at least one starting point and a destination point for an itinerary to be calculated; - calculating, by way of an itinerary calculation module, at least one itinerary between a starting point and an arrival point; - identifying, using a manoeuvre detection module, the manoeuvres along the itinerary; - verifying, for each of the manoeuvres, using a module for testing data specifying a direction to be followed, whether a specification of a direction to be followed is available in the available road map data; - if a specification of a direction to be followed is available in the road map data, extracting, using a data synthesis module, the data specifying a direction to be followed; - if a specification of a direction to be followed is not available in the road map data, generating, using a data synthesis module, from the road map data, geometrical indications of road sections to be travelled, said indications being based on the effective geometry of the sections of the itinerary portion in question; - if a specification of a direction to be followed is available in the road map data, extracting, using a data synthesis module, the data specifying a direction to be followed; - if a specification of a direction to be followed is not available in the road map data, generating, using a data synthesis module, from the road map data, geometrical indications of road sections to be travelled, said indications being based on the effective geometry of the sections of the itinerary portion in question; - generating, using a synthetic map generation module, an itinerary map including, in the order in which the manoeuvres of the itinerary are followed: - for the itinerary portions for which a direction indication is available in the road map data, the extracted data specifying a direction to be followed, provided on their own; - for the itinerary portions for which a specification of a direction to be followed is not available in the road map data, the supplied geometrical indications of sections to be travelled; - for the itinerary portions for which a direction indication is available in the road map data, the extracted data specifying a direction to be followed, provided on their own; - for the itinerary portions for which a specification of a direction to be followed is not available in the road map data, the supplied geometrical indications of sections to be travelled; - transmitting, using a data exchange module, the data of the established synthetic itinerary to at least one mobile navigation device; - supplying, to a user of the mobile navigation device, the data of the synthetic itinerary received from the itinerary server.