Method and system for using real-time traffic broadcasts with navigation systems

A method of operating a navigation system comprising:

• in an in-vehicle navigation system, receiving a plurality of broadcast traffic messages from a traffic broadcast system that broadcasts said traffic messages,
• wherein each of said traffic messages includes a plurality of data components including:
• a first data component that identifies a starting location of traffic congestion, wherein said starting location is a location selected from an ordered sequence of designated locations along a road to which location reference numbers have been assigned,
• a second data component that indicates a severity level of traffic congestion extending from said starting location, and
• a third data component that indicates an extent of the traffic congestion, wherein said extent is expressed as a number of adjacent locations in an ordered sequence of designated locations extending from the starting location;
• in said in-vehicle navigation system, using a geographic database to identity affected road segments that extend from the starting location and from each of the adjacent locations in said ordered sequence of designated locations extending from starting location indicated by the extent;
• associating said affected road segments with the severity level of said second data component;
• and
• using said geographic database to calculate a route to a selected destination taking into account the traffic conditions associated with the affected road segments.

A geographic database used by a navigation system for route calculation in conjunction with traffic messages broadcast by a traffic condition broadcast system wherein each of said traffic messages includes

• a location reference number that indicates a starting location of a reported traffic condition, wherein said location reference number identifies a designated location selected from an ordered sequence of designated locations along a road to which location reference numbers have been assigned, and
• data that indicates an extent of the reported traffic condition, wherein said extent is expressed as a number of adjacent locations in said ordered sequence of designated locations extending from the starting location,
• said geographic database comprising:
• data entities of a first type that represent geographic features in a geographic region, including portions of a road network;
• and
• data entities of a second type each of which associates a location reference number to data entities of said first type that represent road segments that extend therefrom,
• whereby the navigation system using said geographic database in conjunction with traffic messages broadcast by the tic condition broadcast system can incorporate information from said traffic messages when using said geographic database for route calculation purposes.