PROBABILITY OF REAL-TIME DATA AS A FUNCTION OF HOURLY VOLUME, ASSESSMENT OF THE 1-95 VEHICLE PROBE PROJECT DATA

摘要

The Vehicle Probe Project (VPP) is an outsourced traffic monitoring system established by the 1-95 Corridor Coalition and has been active since July 2008. By contractual agreement with the vendor, INRLX Corporation, travel time and speed data are provided to minimum quality specifications whenever traffic flow exceeds 500 vehicles per hour (vph). The monthly validation program has confirmed the quality of the data by comparing VPP data against travel times collected using Bluetooth traffic monitoring equipment, but typically during high volume periods when congestion is likely. Validation has not been confirmed for minimum flow conditions (less than 500 vph) due in part to lack of accurate volume data as well as the low probability of observing traffic congestion at low volumes. The VPP provides an indication of real-time data by the score attribute. When score is equal to 30, the traffic data is based on real-time information. A score less than 30 indicates reliance on historical data. Studies have shown that traffic data based primarily on historical data do not meet minimum quality specifications during moderate and severe congestion. By using volume data from the Maryland State Highway Administration and the Delaware Department of Transportation from permanent count locations, the likelihood of acquiring real-time data (as evidenced by score equal 30) as a function of hourly volume is established.