Traffic-jam state calculation systems, methods, and programs

A traffic jam state calculation system comprising:

• a controller that:
• obtains probe information, the probe information comprising an average speed of probe cars traveling on each of a plurality of links in a predetermined area;
• compares the average speed of each of the plurality of links with each of a plurality of thresholds, each of the plurality of thresholds having a different value;
• based on the comparison, detects, for each of the plurality of links, a first degree of a traffic jam corresponding to the link for each of the plurality of different thresholds;
• obtains traffic jam information concerning the plurality of links, the obtained traffic information comprising a second degree of the traffic jam corresponding to each of the plurality of links;
• compares, for each of the plurality of links, the second degree of the traffic jam with the first degree of the traffic jam for each of the thresholds;
• selects, for the predetermined area, a threshold from the plurality of thresholds for which the first degree of the traffic jam most matches the second degree of the traffic jam, the threshold usable to differentiate a degree of the traffic jam in the predetermined area;
• and
• utilizes the selected threshold to determine a severity of the traffic jam for each of the plurality of links.