January 23, 2006Transportation Research Board 85 th Annual Meeting Using Ground Truth Geospatial Data to Validate Advanced Traveler Information Systems Freeway Travel Time Messages Transportation Research Board Annual Meeting, January 23, 2006 Christopher M. Monsere Department of Civil & Environmental Engineering Portland State University Aaron Breakstone School of Urban Studies & Planning Portland State University Robert L. Bertini Department of Civil & Environmental Engineering Portland State University Dean Deeter Castle Rock Consultants Galen McGill Oregon Department of Transportation

January 23, 2006Transportation Research Board 85 th Annual Meeting Outline Introduction Study Area Archived Data Data Collection Data Analysis Conclusions Next Steps

January 23, 2006Transportation Research Board 85 th Annual Meeting Outline Introduction Study Area Archived Data Data Collection Data Analysis Conclusions Next Steps

January 23, 2006Transportation Research Board 85 th Annual Meeting Project Goal Evaluation of Oregon Department of Transportation (ODOT)’s travel time estimating and reporting capabilities

January 23, 2006Transportation Research Board 85 th Annual Meeting Real-time Travel Time Estimates FHWA policy Variety of technologies –Inductive loop detectors –Microwave radar –Automatic vehicle tag matching –Video detection –License plate matching –Cell phone matching Past research –General accuracy in free-flow conditions –Recurring congestion & incidents more challenging

January 23, 2006Transportation Research Board 85 th Annual Meeting Portland ATMS Freeway surveillance –485 inductive loop detectors (approximately 175 stations)  Dual loop  Mainline lanes  Upstream of on-ramps –135 ramp meters –98 CCTV ATIS –  Real-time speed map  Static CCTV images –18 dynamic message signs (DMS)  3 display travel times

January 23, 2006Transportation Research Board 85 th Annual Meeting Outline Introduction Study Area Archived Data Data Collection Data Analysis Conclusions Next Steps

January 23, 2006Transportation Research Board 85 th Annual Meeting Study Area 15 directional freeway links –I-5 (6) –I-205 (3) –I-84 (2) –US-26 (2) –OR-217 (2) Downtown Portland

January 23, 2006Transportation Research Board 85 th Annual Meeting Travel Time Calculation Influence Area 4  Travel Time 4  Travel Time 1 Influence Area 1  Travel Time 3 Influence Area 3  Travel Time 2 Influence Area 2 Link Travel Time (TT1 + TT2 + TT3 + TT4) Downtown Portland

January 23, 2006Transportation Research Board 85 th Annual Meeting Outline Introduction Study Area Archived Data Data Collection Data Analysis Conclusions Next Steps

January 23, 2006Transportation Research Board 85 th Annual Meeting PORTAL National ITS Architecture ADUS Funded by NSF Direct fiber-optic connection between ODOT and PSU 20-second data –Occupancy –Volume –Speed Customized travel time area –Conforms to TMOC (Portland Regional Transportation Archive Listing)

January 23, 2006Transportation Research Board 85 th Annual Meeting Outline Introduction Study Area Archived Data Data Collection Data Analysis Conclusions Next Steps

January 23, 2006Transportation Research Board 85 th Annual Meeting Experimental Design Analysis of estimates –Plan logical routes –Determine variability Data collection plan –5-10 runs required for most links –4 routes designed –Transitional periods targeted –Groups with 5-7 minute headways –Standard probe vehicle instructions

January 23, 2006Transportation Research Board 85 th Annual Meeting Data Collection Hardware –Palm handheld computers –Magellan GPS devices Software –ITS-GPS  Available at Individual runs and groups of probe vehicles Variety of traffic conditions –45 percent congested –2 notable incidents

January 23, 2006Transportation Research Board 85 th Annual Meeting Data Collection 87 probe vehicle runs 904 minutes (~15 hours) of collection time 516 miles of data 12 drivers 7 days (Wed – Fri)

January 23, 2006Transportation Research Board 85 th Annual Meeting Outline Introduction Study Area Archived Data Data Collection Data Analysis Conclusions Next Steps

January 23, 2006Transportation Research Board 85 th Annual Meeting Probe Vehicle Data Individual runs downloaded –“run” = several links + extraneous data Unique ID for each GPS record Runs plotted on freeway network –Links color-coded Pertinent data segments extracted last point on Link 9 last point on Link 2 first point on Link 3

January 23, 2006Transportation Research Board 85 th Annual Meeting Matching Estimates Nearest 20-second interval –e.g. 9:15:34  9:15:20 Aggregation –Averages more realistic to operation of system  Average of nearest interval and 1 minute prior  Average of nearest interval and 3 minutes prior

January 23, 2006Transportation Research Board 85 th Annual Meeting Probe vs. Estimated Travel Times Average of previous 3 minutes

January 23, 2006Transportation Research Board 85 th Annual Meeting Results

January 23, 2006Transportation Research Board 85 th Annual Meeting Outline Introduction Study Area Archived Data Data Collection Data Analysis Conclusions Next Steps

January 23, 2006Transportation Research Board 85 th Annual Meeting Conclusions Estimates reasonably accurate given current system configuration –Many within 20% of probe times –Less so under congested conditions –Incidents produced highest error Averaging improves accuracy Detector density and location critical

January 23, 2006Transportation Research Board 85 th Annual Meeting Conclusions Detector density and location critical Estimated Travel Time: ~25.5 minutesProbe Travel Time: ~14.5 minutes Probe Projection Influence Area Limit Probe Travel Time: ~11 minutesEstimated Travel Time: ~9.5 minutes

January 23, 2006Transportation Research Board 85 th Annual Meeting Conclusions Incidents difficult to capture

January 23, 2006Transportation Research Board 85 th Annual Meeting Outline Introduction Study Area Archived Data Data Collection Data Analysis Conclusions Next Steps

January 23, 2006Transportation Research Board 85 th Annual Meeting Next Steps More data –Targeted conditions –Fill gaps  Incidents  Software/hardware issues –Up-to-date Different algorithms –Historical data –Other detectors

January 23, 2006Transportation Research Board 85 th Annual Meeting Acknowledgements ODOT –Stacy Shetler –Dennis Mitchell –Jack Marchant –Hau Hagedorn Student Drivers PSU Department of Civil and Environmental Engineering