Capacity and the Breakdown Phenomenon at a Freeway Merge Bottleneck: Unlocking the Potential of Loop Sensor Data Robert L. Bertini Department of Civil & Environmental Engineering Portland State University February 22, 2002 Robert L. Bertini Department of Civil & Environmental Engineering Portland State University February 22, 2002

2 “Let Knowledge Serve the City” OutlineOutline IntroductionIntroduction Previous StudiesPrevious Studies MethodMethod DataData ResultsResults SummarySummary ImplicationsImplications Ongoing and Future ResearchOngoing and Future Research IntroductionIntroduction Previous StudiesPrevious Studies MethodMethod DataData ResultsResults SummarySummary ImplicationsImplications Ongoing and Future ResearchOngoing and Future Research

3 “Let Knowledge Serve the City” IntroductionIntroduction Research QuestionResearch Question – –Empirically examine evolution of traffic from free flow to queued conditions at a freeway bottleneck downstream of a merge. Exciting OpportunityExciting Opportunity –Bottlenecks are critical nodes in system. –First sixty years: »Promising theories (e.g., Lighthill-Whitham-Richards, Edie, Newell) needed validation. »Difficult to collect data. »Fundamental uncertainties. –Today: »Sensor-rich, “too much” data »Understand traffic behavior »Building blocks for proposing/validating models Research QuestionResearch Question – –Empirically examine evolution of traffic from free flow to queued conditions at a freeway bottleneck downstream of a merge. Exciting OpportunityExciting Opportunity –Bottlenecks are critical nodes in system. –First sixty years: »Promising theories (e.g., Lighthill-Whitham-Richards, Edie, Newell) needed validation. »Difficult to collect data. »Fundamental uncertainties. –Today: »Sensor-rich, “too much” data »Understand traffic behavior »Building blocks for proposing/validating models

4 “Let Knowledge Serve the City” Research Implications Understand traffic behavior at a merge.Understand traffic behavior at a merge. Demonstrate benefits of traffic management sensor investment for research.Demonstrate benefits of traffic management sensor investment for research. Reveal benefits of archived raw data.Reveal benefits of archived raw data. Method for unequivocally pinpointing active bottleneck.Method for unequivocally pinpointing active bottleneck. Resolve two-capacity issue.Resolve two-capacity issue. Potential for future research:Potential for future research: –Improve macroscopic models. –Assess ramp metering. –Enhance freeway management. –Update design standards. Understand traffic behavior at a merge.Understand traffic behavior at a merge. Demonstrate benefits of traffic management sensor investment for research.Demonstrate benefits of traffic management sensor investment for research. Reveal benefits of archived raw data.Reveal benefits of archived raw data. Method for unequivocally pinpointing active bottleneck.Method for unequivocally pinpointing active bottleneck. Resolve two-capacity issue.Resolve two-capacity issue. Potential for future research:Potential for future research: –Improve macroscopic models. –Assess ramp metering. –Enhance freeway management. –Update design standards.

5 “Let Knowledge Serve the City” Active Bottleneck Discharging from upstream queue (maximum).Discharging from upstream queue (maximum). Not impeded by downstream effects.Not impeded by downstream effects. Discharging from upstream queue (maximum).Discharging from upstream queue (maximum). Not impeded by downstream effects.Not impeded by downstream effects.

6 “Let Knowledge Serve the City” Previous Studies Data from fixed pointsData from fixed points –Bivariate plots –Scatter plots Time dependencies & statistical fluctuationsTime dependencies & statistical fluctuations –Short time intervals –Long time intervals Data from fixed pointsData from fixed points –Bivariate plots –Scatter plots Time dependencies & statistical fluctuationsTime dependencies & statistical fluctuations –Short time intervals –Long time intervals

7 “Let Knowledge Serve the City” MethodMethod Flow Time, x N(x,t)

8 “Let Knowledge Serve the City” MethodMethod

9 MethodMethod

10 “Let Knowledge Serve the City” Cumulative Curves

11 “Let Knowledge Serve the City” Skewed Cumulative Curves

12 “Let Knowledge Serve the City” Site – Gardiner Expressway

13 “Let Knowledge Serve the City” Occupancy Data

14 “Let Knowledge Serve the City” Loop Sensor Data Validation

15 “Let Knowledge Serve the City” Loop Sensor Data Validation

16 “Let Knowledge Serve the City” Pinpointing the Bottleneck

17 “Let Knowledge Serve the City” Queue Presence

18 “Let Knowledge Serve the City” Bottleneck Deactiviation

19 “Let Knowledge Serve the City” Estimating Bottleneck Capacity

20 “Let Knowledge Serve the City” ReproducibilityReproducibility

21 “Let Knowledge Serve the City” Active Bottleneck Under Different Conditions

22 “Let Knowledge Serve the City” ReproducibleReproducible

23 “Let Knowledge Serve the City” Precursors to Breakdown

24 “Let Knowledge Serve the City” SummarySummary Benefits from applying method to archived sensor data.Benefits from applying method to archived sensor data. Bottleneck location fixed: 1 km downstream of ramp.Bottleneck location fixed: 1 km downstream of ramp. Resolved two-capacity issue: high flow prior to queue formation.Resolved two-capacity issue: high flow prior to queue formation. Tell-tale breakdown signal.Tell-tale breakdown signal. Measured capacity: average discharge flow.Measured capacity: average discharge flow. Benefits from applying method to archived sensor data.Benefits from applying method to archived sensor data. Bottleneck location fixed: 1 km downstream of ramp.Bottleneck location fixed: 1 km downstream of ramp. Resolved two-capacity issue: high flow prior to queue formation.Resolved two-capacity issue: high flow prior to queue formation. Tell-tale breakdown signal.Tell-tale breakdown signal. Measured capacity: average discharge flow.Measured capacity: average discharge flow.

25 “Let Knowledge Serve the City” ConclusionsConclusions Importance of bottlenecks.Importance of bottlenecks. Robust method.Robust method. Greater understanding of merge bottlenecks.Greater understanding of merge bottlenecks. Contributions:Contributions: –Empirical approach. –Metering, managing and modeling. –ATIS, ATMS, and ADUS Importance of bottlenecks.Importance of bottlenecks. Robust method.Robust method. Greater understanding of merge bottlenecks.Greater understanding of merge bottlenecks. Contributions:Contributions: –Empirical approach. –Metering, managing and modeling. –ATIS, ATMS, and ADUS

26 “Let Knowledge Serve the City” Ongoing Research Toronto merge trajectoriesToronto merge trajectories Lane drop bottleneckLane drop bottleneck –London –Minneapolis –Other bottlenecks Toronto merge trajectoriesToronto merge trajectories Lane drop bottleneckLane drop bottleneck –London –Minneapolis –Other bottlenecks

27 “Let Knowledge Serve the City” Ongoing Research

28 “Let Knowledge Serve the City” Example Projects Portland Advanced Traffic Management System (TransPort)Portland Advanced Traffic Management System (TransPort) –90 ramp meters –400 inductive loop detectors –49 CCTV cameras –13 variable message signs Using archived data to demonstrate value of archiving, and expanding possibilities for generating information useful for planners, engineers, policymakers and ultimately the users via ATISUsing archived data to demonstrate value of archiving, and expanding possibilities for generating information useful for planners, engineers, policymakers and ultimately the users via ATIS Monica Leal, MS StudentMonica Leal, MS Student Portland Advanced Traffic Management System (TransPort)Portland Advanced Traffic Management System (TransPort) –90 ramp meters –400 inductive loop detectors –49 CCTV cameras –13 variable message signs Using archived data to demonstrate value of archiving, and expanding possibilities for generating information useful for planners, engineers, policymakers and ultimately the users via ATISUsing archived data to demonstrate value of archiving, and expanding possibilities for generating information useful for planners, engineers, policymakers and ultimately the users via ATIS Monica Leal, MS StudentMonica Leal, MS Student Using Archived ITS Data for Transportation Performance Measures Oregon Department of Transportation Using Archived ITS Data for Transportation Performance Measures Oregon Department of Transportation

29 “Let Knowledge Serve the City” Example Projects Using Archived Data to Measure Operational Benefits of Intelligent Transportation System Investments U.S. Department of Transportation (TransNow) and ODOT Use existing data, surveillance and communications infrastructureUse existing data, surveillance and communications infrastructure Two case study evaluations for OregonTwo case study evaluations for Oregon –COMET incident management program –Portland ramp metering system. Set precedent for future evaluations of ITS programs.Set precedent for future evaluations of ITS programs. Using Archived Data to Measure Operational Benefits of Intelligent Transportation System Investments U.S. Department of Transportation (TransNow) and ODOT Use existing data, surveillance and communications infrastructureUse existing data, surveillance and communications infrastructure Two case study evaluations for OregonTwo case study evaluations for Oregon –COMET incident management program –Portland ramp metering system. Set precedent for future evaluations of ITS programs.Set precedent for future evaluations of ITS programs.

30 “Let Knowledge Serve the City” Example Projects Alternatives to Motor Fuel Tax Oregon Department of Transportation Collaboration with Professor T. Rufolo, Urban and Regional PlanningCollaboration with Professor T. Rufolo, Urban and Regional Planning Fuel tax revenue declining with fuel efficient/alternative fuel vehiclesFuel tax revenue declining with fuel efficient/alternative fuel vehicles Other road finance measures under considerationOther road finance measures under consideration Consider fee based on vehicle miles traveledConsider fee based on vehicle miles traveled Three goals of this phase:Three goals of this phase: –Validate alternative financing mechanisms –Evaluate technologies for assessing alternative fees –Consider transition issues to new system –Minimize equity concerns Alternatives to Motor Fuel Tax Oregon Department of Transportation Collaboration with Professor T. Rufolo, Urban and Regional PlanningCollaboration with Professor T. Rufolo, Urban and Regional Planning Fuel tax revenue declining with fuel efficient/alternative fuel vehiclesFuel tax revenue declining with fuel efficient/alternative fuel vehicles Other road finance measures under considerationOther road finance measures under consideration Consider fee based on vehicle miles traveledConsider fee based on vehicle miles traveled Three goals of this phase:Three goals of this phase: –Validate alternative financing mechanisms –Evaluate technologies for assessing alternative fees –Consider transition issues to new system –Minimize equity concerns

31 “Let Knowledge Serve the City” Highway 18 and I-5Highway 18 and I-5 Using archived data to measure effectiveness of existing program and assist ODOT in decision- making for future expansion of program to additional highway routes.Using archived data to measure effectiveness of existing program and assist ODOT in decision- making for future expansion of program to additional highway routes. Highway 18 and I-5Highway 18 and I-5 Using archived data to measure effectiveness of existing program and assist ODOT in decision- making for future expansion of program to additional highway routes.Using archived data to measure effectiveness of existing program and assist ODOT in decision- making for future expansion of program to additional highway routes. Example Projects Evaluation of Rural/Urban Incident Response Programs Oregon Department of Transportation Region 2 Evaluation of Rural/Urban Incident Response Programs Oregon Department of Transportation Region 2

32 “Let Knowledge Serve the City” Prototype for Advanced Public Transit Systems in Multimodal Corridor Great Cities Universities Coalition: Federal Transit Administration Multi-disciplinary/multi-university team:Multi-disciplinary/multi-university team: PSU Civil EngineeringPSU Civil Engineering PSU Urban StudiesPSU Urban Studies City College of New York/City University of New YorkCity College of New York/City University of New York Northwestern UniversityNorthwestern University University of Alabama, BirminghamUniversity of Alabama, Birmingham Interstate 5/Barbur Blvd. CorridorInterstate 5/Barbur Blvd. Corridor Testing strategies for improving transit operationsTesting strategies for improving transit operations and passenger information systems and passenger information systems Prototype for Advanced Public Transit Systems in Multimodal Corridor Great Cities Universities Coalition: Federal Transit Administration Multi-disciplinary/multi-university team:Multi-disciplinary/multi-university team: PSU Civil EngineeringPSU Civil Engineering PSU Urban StudiesPSU Urban Studies City College of New York/City University of New YorkCity College of New York/City University of New York Northwestern UniversityNorthwestern University University of Alabama, BirminghamUniversity of Alabama, Birmingham Interstate 5/Barbur Blvd. CorridorInterstate 5/Barbur Blvd. Corridor Testing strategies for improving transit operationsTesting strategies for improving transit operations and passenger information systems and passenger information systems Example Projects

33 “Let Knowledge Serve the City” Example Projects Using Transit Vehicles as Traffic Probes Tri-Met Tri-Met

34 “Let Knowledge Serve the City” PSU Civil EngineeringPSU Civil Engineering PSU Urban Studies and PlanningPSU Urban Studies and Planning OHSU Department of Emergency MedicineOHSU Department of Emergency Medicine PSU School of Community HealthPSU School of Community Health City of PortlandCity of Portland Multnomah County EMSMultnomah County EMS Oregon Department of Health ServicesOregon Department of Health Services Oregon State PoliceOregon State Police Tri-MetTri-Met Tualatin Valley Fire and RescueTualatin Valley Fire and Rescue Willamette Pedestrian Coalition Willamette Pedestrian Coalition PSU Civil EngineeringPSU Civil Engineering PSU Urban Studies and PlanningPSU Urban Studies and Planning OHSU Department of Emergency MedicineOHSU Department of Emergency Medicine PSU School of Community HealthPSU School of Community Health City of PortlandCity of Portland Multnomah County EMSMultnomah County EMS Oregon Department of Health ServicesOregon Department of Health Services Oregon State PoliceOregon State Police Tri-MetTri-Met Tualatin Valley Fire and RescueTualatin Valley Fire and Rescue Willamette Pedestrian Coalition Willamette Pedestrian Coalition Example Proposal Creating Safe and Sustainable Neighborhoods for Pedestrians and Bicyclists A Great City: Great University Partnership Creating Safe and Sustainable Neighborhoods for Pedestrians and Bicyclists A Great City: Great University Partnership

35 “Let Knowledge Serve the City” New Potential Project Integrated E911/Emergency Response/Transportation Network Oregon Testbed: First demonstration in the nationOregon Testbed: First demonstration in the nation Partnerships: Intel, Senator Wyden, Comcare Alliance, EMS, 911, Transportation Agencies, PSUPartnerships: Intel, Senator Wyden, Comcare Alliance, EMS, 911, Transportation Agencies, PSU Integrated E911/Emergency Response/Transportation Network Oregon Testbed: First demonstration in the nationOregon Testbed: First demonstration in the nation Partnerships: Intel, Senator Wyden, Comcare Alliance, EMS, 911, Transportation Agencies, PSUPartnerships: Intel, Senator Wyden, Comcare Alliance, EMS, 911, Transportation Agencies, PSU

36 “Let Knowledge Serve the City” Vision for Real-Time Traffic Management Center

37 “Let Knowledge Serve the City” ConclusionConclusion Thank You!