1. NATMEC June 5, 2006 Comparative Analysis Of Various Travel Time Estimation Algorithms To Ground Truth Data Using Archived Data Christopher M. Monsere Research Assistant Professor Dept of Civil and Environmental Engineering Portland State University Sirisha Kothuri, Kristin Tufte, Robert L. Bertini, School of Urban & Public Affairs Portland State University Comparative Analysis Of Various Travel Time Estimation Algorithms To Ground Truth Data Using Archived Data Christopher M. Monsere Sirisha Kothuri, Kristin Tufte, Robert L. Bertini, Aaron Breakstone Department of Civil & Environmental Engineering Intelligent Transportation Systems Laboratory Portland State University NATMEC June 5, 2006 Minneapolis, Minnesota

2. NATMEC June 5, 2006 Outline Introduction Study Area Data Sources Data Analysis Preliminary Conclusions Next Steps

3. NATMEC June 5, 2006 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 FHWA policy on DMS Real-time Travel Time Estimates

4. NATMEC June 5, 2006 Portland ATMS Freeway surveillance –485 inductive loop detectors Dual loop Mainline lanes Upstream of on-ramps –135 ramp meters –98 CCTV Traveler information www.TripCheck.com Real-time speed map Static CCTV images –18 Dynamic Message Signs (DMS) 3 display travel times

5. NATMEC June 5, 2006 Objectives Build on recent evaluation of Oregon Department of Transportation (ODOT)’s travel time estimating and reporting capabilities Test other algorithms on select links using historical data

6. NATMEC June 5, 2006 Study Area 9 directional freeway links –I-5 (3) –I-205 (3) –I-84 (1) –OR-217 (2)

7. NATMEC June 5, 2006 Probe Vehicle Data collected –Standard probe vehicle instructions (FHWA) –5-10 runs –Transitional periods targeted –Groups with 5-7 minute headways Measures –87 probe vehicle runs –15 hours –516 miles –7 days (Wed – Fri)

8. NATMEC June 5, 2006 Probe Vehicle Hardware –Palm handheld computers –Magellan GPS devices Software –ITS-GPS  Available at www.its.pdx.edu Individual runs and groups of probe vehicles Variety of traffic conditions –45 percent congested –2 notable incidents

9. NATMEC June 5, 2006 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

10. NATMEC June 5, 2006 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) www.portal.its.pdx.edu

11. NATMEC June 5, 2006 Travel Time – Midpoint Algorithm Influence Area i  Travel Time i (at t = 0)  Travel Time 1  (at t = 0) 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 + TTi)

12. NATMEC June 5, 2006 Travel Time - Coifman Algorithm Time Distance downstream detector upstream detector

13. NATMEC June 5, 2006 Methodology – Implementation Coifman u/s Coifman d/s Coifman - midpt Coifman - distwt Midpoint Midpoint Average

14. NATMEC June 5, 2006 Analysis – Link 3 Trajectories (Uncongested)

15. NATMEC June 5, 2006 Analysis – Link 6 Trajectories (Large Spacing)

16. NATMEC June 5, 2006 Analysis – Link 8 Trajectories (Incident)

17. NATMEC June 5, 2006 Analysis – Probe Vehicle, Coifman, Midpoint Link 3 Link 4

18. NATMEC June 5, 2006 Results - Incident Travel Times Lowest Error

19. NATMEC June 5, 2006 Analysis - Coifman & Midpoint Errors

20. NATMEC June 5, 2006 Conclusions Coifman estimated travel times are more accurate than midpoint travel times –Both algorithms estimate travel times fairly accurately during free flow conditions The accuracy is related to –Location and density of detectors –Location, formation and dissipation of queue Incidents & large spacing between detectors result in larger error in midpoint travel time estimates

21. NATMEC June 5, 2006 Next Steps Further testing of Coifman and Midpoint under varying traffic conditions Expand Coifman algorithm from current historical analysis to real time estimates Comparison to ODOT range of travel times Data quality??

22. NATMEC June 5, 2006 Acknowledgements Castle Rock Consultants –Dean Deeter ODOT –Galen McGill –Stacy Shetler PORTAL Team Volunteer Drivers