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True Adaptive Signal Control A Comparison of Alternatives Technical Paper #1154

1. True Adaptive Signal Control A Comparison of Alternatives Technical Paper #1154. Presentation to the 18 th World Congress on Intelligent Transport Systems Technical Session 95 (TS95) Wednesday 19 October 2011. Authors. Cary Vick, PE – Telvent Transportation (presenting)

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True Adaptive Signal Control A Comparison of Alternatives Technical Paper #1154

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  1. 1 True Adaptive Signal Control A Comparison of Alternatives Technical Paper #1154 Presentation to the 18th World Congress on Intelligent Transport Systems Technical Session 95 (TS95) Wednesday 19 October 2011

  2. Authors Cary Vick, PE – Telvent Transportation (presenting) Farhad Pooran, PE, PhD - Telvent Transportation José Carlos Riveira Martinez - Telvent Trafico y Transporte

  3. Purpose / Agenda • Clarify definitions and capabilities of true adaptive signal control • Urge selection of some type of advanced signal control • We can do better with what we have • It’s not just for research any more • Summarize approach of available technologies / products • Not a comprehensive review and comparison of results

  4. Deployment of Adaptive Signal Control Technologies SCATS RHODES ACSLite InSync LA ATCS State with Pending ASCT SCOOT OPAC State with Active ASCT

  5. Categories of Signal Control • The primary differentiator for Traffic Adaptive Control is the use of a traffic flow model to predict demand and adapt timings to meet expected traffic flows • Definitions (USDOT / FHWA Traffic Signal Control Handbook (Gordon and Tighe)): • Isolated • Time Based Coordination • Interconnected Control • Traffic Adjusted Control • Traffic Responsive Control • Traffic Adaptive Control

  6. What is NOT Adaptive Control • All approaches have value, but they are NOT adaptive signal control • Traffic Responsive: • Trigger plan or timing changes • Volume Density: • Modify parameters based on demand • Off-line Optimization: • Real time measurements trigger re-optimization of timing plans • Central + Local Optimization: • Real time measurements trigger re-optimization of selected timing parameters (off set) then local control applies and adjusts

  7. Summary of ASCT Alternatives

  8. Adaptive Traffic Signal Control Processes A or B CycleOptimizer Offset Optimizer Split Optimizer Traffic Engineer Expert Rules Offset weights Split weights Cycle weights Platoon modeling A + B Occupancy Volume B Intersection control A

  9. Operations of AdaptiveSignal Control Control Center Operator / Traffic Engineer € Traffic Flow / Queue Model Traffic data at detection ponts Intersection structure € ¹ Mean travel time Queue lengths Exit flows Queue capacity Pro Active Timing Changes Real Time Data Street Observer for Calibration

  10. Weighting Factors Apply Expert Rules to Adaptive Control Strategies Reduce weight for Transversal Route B Route A is highly congested Intersection B20 has maximum queue Then Until If • ITACA Expert Rules System • Usable range is -10 to +10 • Positive weights apply importance to affected links • Negative weights reduce importance of associated links • 2 weighting parameters for each link (split and offset) • 1 weighting parameter for each intersection (cycle) • Can be adjusted in real time manually or by expert rules • Each final weight may reflect adjustments by different sources

  11. OPAC Hardware Configuration • Advanced Traffic Controllers • OPAC Single Board Computer (local) • Upstream Advance Detectors Cabinet Traffic Signal Controller: Type 2070 or NEMA (TS1 / TS2) Detector Data Force offs & Holds Single Board Computer (Linux OS) running OPAC software

  12. ACS-Lite Architecture ACS-Lite Computer Minimum 9600 baud Communications (serial or IP) NTCIP On-street Master (optional) Communications Interface and/or NTCIP Translators NTCIP controllers or Proprietary protocol controllers

  13. Advantages of Predictive Modeling • The primary differentiator for Traffic Adaptive Control is the use of a traffic flow model to predict demand and adapt timings to meet expected traffic flows Continuous adjustment to changing demand Pro-active timing changes Optimal use of available capacity Adjusts to incident conditions

  14. Cycle Length Adaptability Incident Occurs

  15. References: • Stevanovic, Aleksandar, “Adaptive Traffic Control Systems: Domestic and Foreign State of Practice” NCHRP Synthesis 403, Transportation Research Board, Washington, DC, 2010 • Gordon, Robert L, and Tighe, Warren “Traffic Control Systems Handbook.” Federal Highway Administration Report FHWA-HOP-06-006, Washington, DC, 2005. • Gartner, N.H., F.J. Poorhan, and C.M. Andrews. “Implementations and Field Testing of the OPAC Adaptive Control Strategy in RT-TRACS.” TRB Paper No. 02-3667 - Presented at the 81st Annual Meeting of the Transportation Research Board, Washington, DC, 2002. • Riveira Martínez, José Carlos. “The Road to ITACA”, internal white paper, Telvent, 2000. • MacGowan, J., and I. J. Fullerton. 1979. Development and testing of advanced control strategies in the urban traffic control system. Public Roads 43, no. 2, 3, and 4.

  16. Thank You Smart Information for a Sustainable World

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