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A case–driven comparison of Freeway Performance Measurement Systems

A case–driven comparison of Freeway Performance Measurement Systems. by Shailesh Deshpande. National Cooperative Highway Research Program (NCHRP) report.

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A case–driven comparison of Freeway Performance Measurement Systems

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  1. A case–driven comparison of FreewayPerformance Measurement Systems by Shailesh Deshpande

  2. National Cooperative Highway Research Program (NCHRP) report • Provides transportation engineers and planners assistance in developing and maintaining a comprehensive freeway performance monitoring program • Emphasis on – Congestion and Mobility Performance • Other aspects of freeway performance • Safety • Operational Efficiency • Ride quality • Environmental impact • Customer Satisfaction

  3. NCHRP report contd.. • Tries to answer following four questions about freeway performance: • What measures should be used? • How can the measures be developed with data and models? • How should freeway performance be communicated? • How can freeway performance measures be used in decision-making?

  4. Conclusions • Performance measurement of all kinds is growing in importance and is becoming institutionalized within transportation agencies. • Collection of quality data is required to build the foundation of a freeway performance measurement program. • Congestion and mobility performance measurement on freeways has been the largest gap in knowledge. • Travel time reliability is being recognized as characteristic of congestion that is on equal footing with average congestion levels. • Measuring average congestion and overall travel time reliability is only the start of understanding congestion and crafting strategies to deal with it • Quality of service and performance measures must be linked together and tied into the mission of the transportation agency • The Guidebook is a reference rather than a prescriptive document – local issues may be different and state-of-the-art is not mature

  5. Two types of Performance Measures • Quality of Service (Outcome): relates to how well the firm or agency is meeting its mission and stated goals • Activity-Based (Output): relate to the physical quantities of items; levels of effort expended, scale or scope of activities and the efficiency in converting resources into some kind of product (a.k.a Efficiency Measures)

  6. Freeway Performance MeasurementProgram Timescales

  7. National Transportation Operations Coalition (NTOC) recommended measures • Customer Satisfaction • Extent of Congestion – Spatial • Extent of Congestion – Temporal • Incident Duration • Nonrecurring Delay • Recurring Delay • Speed • Throughput – Person • Throughput – Vehicle • Travel Time – Link • Travel Time –Reliability (Buffer Time) • Travel Time – Trip

  8. American Society for Testing and Materials (ASTM) recommended measures • Volume • Flow Rate • Detector Occupancy • Speed • Percentile Speed • Pace • Percent within Pace • Travel Time • Traffic Density • Level of Service • Number of stops • Stopped delay

  9. NCHRP recommended performance measures • Core :Travel Time, Travel Time Index, Total Delay(Vehicles), Total Delay (Persons), Delay per Vehicle, Spatial Extent of Congestion, Temporal Extent of Congestion, Density… • Supplemental : Bottleneck delay, Incident delay, Work Zone delay, Weather delay, Ramp delay, Volume-to-capacity ratio…

  10. Systems under consideration • Freeway Performance Measurement System (PeMS) – UC Berkeley, PATH, Caltrans https://pems.eecs.berkeley.edu/?redirect=%2F%2F%3Fdnode%3DState • Highway Operation Monitoring and Evaluation System (HOMES) – VDOT, VTRC, Smart Traffic Center, Virginia Tech http://208.22.18.20/realtimetraffictesting/ • Regional Integrated Transportation Information System (RITIS) – UMD’s Center for Advanced Transportation Technology (CATT) – www.ritis.org

  11. Proposal • The best (or worst) thing about measures is that there are so many to choose from! • Focus on Real-time and Near-term data • Most relevant to transportation officials & drivers • Not all systems have the kind of long-term data that would support planning decisions • In the absence of consistent measures use a case-driven approach: • Identify the set of most relevant cases that interest a transportation official (Accidents, Lane closures, Public Events, Snow etc.) • Which performance measures are applicable for each of these cases? • How do the 3 systems compare when communicating this information? • How do they aggregate data?

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