1.1.2.5: Process Vehicle Situation Data

This process shall be responsible for processing vehicle probe data collected from roadside short range communications equipment and centers controlling transit vehicles, toll collection points, and route-guided vehicles. This process shall calculate vehicle speed per network link based upon the vehicle data input. The traffic situation and sensor data could be obtained from a process that measures the presence of vehicles at locations along the network (e.g. using a vehicle tag), or directly from equipment onboard vehicles that measure vehicle speed and other parameters. The data could also be obtained from a fleet of vehicles that are using an automated vehicle location function to track the location of the vehicles (e.g. a transit fleet). Finally, the data could be obtained from an analysis of toll transaction records. Based upon data inputs received, this process shall calculate the travel time for the links for which data has been provided. In the case of direct measurement of vehicle location (e.g. the tag and reader approach) this shall be achieved by noting the successive times at which the tag data is received and calculating the travel time from the difference. The process shall maintain a data store that contains the average travel time for each link in the freeways, surface streets, and rural roadways that is calculated from one of the above forms of probe data. Calculation of the actual average values shall employ some type of aggregation processing (e.g., smoothing or similar technique) and be stored for differing time categories (e.g., times of day, day of week, holidays) in periodic increments. The current delay time for a link shall be the difference between current travel time value and the aggregate processed (e.g., average) value for that time category. This process shall determine when a vehicle is going in the wrong way relative to the normal/prescribed flow of traffic based on the received vehicle location and motion messages and through receipt of direct wrong way warming messages. This process shall forward indications of a wrong way vehicle to the process Monitoring Vehicle Direction Movement.

This process is associated with the ITS Roadway Equipment physical object.

This process is associated with the following functional objects:

• Roadway Wrong Way Vehicle Detection
• TMC Basic Surveillance
• TMC Environmental Monitoring
• TMC Signal Control
• TMC Situation Data Management
• TMC Speed Warning
• TMC Traffic Gap Assist
• TMC Variable Speed Limits

This process is associated with the following data flows:

• env_vehicle_sensor_data_for_traffic
• fwcps-travel_time_data_for_traffic
• link_data_from_probes
• local_travel_times_data_for_traffic
• probe_data_for_strategy
• toll_probe_data_for_traffic
• traffic_probe_info_for_traffic
• transit_probe_data_for_traffic
• vehicle_situation_data_at_border
• vehicle_situation_data_for_traffic
• vehicle_traffic_data_for_center