February 9, 2006TransNow Student Conference Using Ground Truth Geospatial Data to Validate Advanced Traveler Information Systems Freeway Travel Time Messages TransNow Student Conference, February 9, 2006 Aaron Breakstone Master of Urban & Regional Planning Candidate School of Urban Studies & Planning Portland State University Christopher M. Monsere, Ph.D., P.E. Research Assistant Professor Department of Civil & Environmental Engineering Portland State University Robert L. Bertini, Ph.D., P.E. Associate Professor Department of Civil & Environmental Engineering School of Urban Studies & Planning Portland State University

February 9, 2006TransNow Student Conference Outline Introduction Study Area Archived Data Data Collection Data Analysis Conclusions Next Steps

February 9, 2006TransNow Student Conference Outline Introduction Study Area Archived Data Data Collection Data Analysis Conclusions Next Steps

February 9, 2006TransNow Student Conference Project Goal Evaluation of Oregon Department of Transportation (ODOT)’s travel time estimating and reporting capabilities

February 9, 2006TransNow Student Conference 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

February 9, 2006TransNow Student Conference 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

February 9, 2006TransNow Student Conference Outline Introduction Study Area Archived Data Data Collection Data Analysis Conclusions Next Steps

February 9, 2006TransNow Student Conference Study Area 15 directional freeway links –I-5 (6) –I-205 (3) –I-84 (2) –US-26 (2) –OR-217 (2) Downtown Portland

February 9, 2006TransNow Student Conference Travel Time Calculation Influence Area 4  Travel Time 4 (at t = 0)  Travel Time 1 Influence Area 1  Travel Time 3 (at t = 0) Influence Area 3  Travel Time 2 (at t = 0) Influence Area 2 Link Travel Time (TT1 + TT2 + TT3 + TT4) Downtown Portland

February 9, 2006TransNow Student Conference Outline Introduction Study Area Archived Data Data Collection Data Analysis Conclusions Next Steps

February 9, 2006TransNow Student Conference 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)

February 9, 2006TransNow Student Conference Outline Introduction Study Area Archived Data Data Collection Data Analysis Conclusions Next Steps

February 9, 2006TransNow Student Conference 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 (FHWA)

February 9, 2006TransNow Student Conference 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

February 9, 2006TransNow Student Conference Data Collection 87 probe vehicle runs 904 minutes (~15 hours) of collection time 516 miles of data 12 drivers 7 days (Wed – Fri)

February 9, 2006TransNow Student Conference Outline Introduction Study Area Archived Data Data Collection Data Analysis Conclusions Next Steps

February 9, 2006TransNow Student Conference 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

February 9, 2006TransNow Student Conference 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

February 9, 2006TransNow Student Conference Probe vs. Estimated Travel Times Average of previous 3 minutes

February 9, 2006TransNow Student Conference Results

February 9, 2006TransNow Student Conference Outline Introduction Study Area Archived Data Data Collection Data Analysis Conclusions Next Steps

February 9, 2006TransNow Student Conference 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

February 9, 2006TransNow Student Conference 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

February 9, 2006TransNow Student Conference Conclusions Incidents difficult to capture Δ = ~7 minutes Δ = ~12.5 minutes

February 9, 2006TransNow Student Conference Outline Introduction Study Area Archived Data Data Collection Data Analysis Conclusions Next Steps

February 9, 2006TransNow Student Conference Next Steps More data –Targeted conditions –Fill gaps  Incidents  Software/hardware issues –Up-to-date Different algorithms –Historical data –Data from other detectors

February 9, 2006TransNow Student Conference Acknowledgements ODOT –Galen McGill –Stacy Shetler –Dennis Mitchell –Jack Marchant –Hau Hagedorn Castle Rock Consultants –Dean Deeter Student Drivers