Patent ID: 6810321
Filing Date: 2004-10-26
Classification: G08G

Abstract:
A vehicular traffic monitoring system for communicating with a plurality of mobile telephones carried in moving vehicles and capable of determining their respective geographic positions and velocities, comprising:a data collector for receiving data samples from said plurality of mobile telephones, each data sample comprising instantaneous location and velocity information of a respective mobile telephone at a respective time; a road segment identifier coupled to said data collector for finding matching data samples wherein a respective instantaneous location corresponds to one of a plurality of road segments monitored by said traffic monitoring system; a recursive sliding average calculator coupled to said road segment identifier for determining an average speed corresponding to matched data samples for a particular one of said road segments in response to a predetermined sliding window having a predetermined number of said matched data samples wherein said average speed is determined as a recursive sliding average An in response to an nth one of said matched data samples Sn, a previous average speed Anâˆ’1, and a predetermined number W of matched data samples in said predetermined sliding window; a state change detector coupled to said recursive sliding average calculator for detecting a traffic state change at said road segment in response to said average speed in said predetermined sliding window determined at first and second times; and a congestion indicator coupled to said state change detector, said congestion indicator indicating either a congested state or a clear state of said respective road segment in response to said detected traffic state change.