| 摘要 |
A system for determining traffic information comprises a map acquiring unit and a traffic information acquiring unit. The map unit is configured to acquire map information which includes speed limit data for a plurality or road links. The traffic unit acquires traffic messages from a traffic information centre about the congestion state of a road section and may also include an average speed for the congested section. In use, a determination of traffic congestion uses the congestion rating from the centre if the average speed is not included in the message (S50, S90). If an average speed is included and no speed limit data is found then the average speed is used to determine the degree of congestion (S60, S80). If the average speed information and speed limit information are both present then the determination is based on both values (S70). The device may include a storage means for storing a correspondence between average speeds and traffic congestion for road links (Fig 3b). Further apparatus may include a means for notifying the use of the degree of congestion for the road section (S100). |
