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Improved Traffic Signal Efficiency in Rural Areas through Variable Maximum Green Time

This research study evaluates the use of Variable Maximum Green Time (VMGT) as a way to reduce delay and increase throughput at isolated intersections in rural areas. The study includes site selection, methodology, simulation results, and conclusions.

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Improved Traffic Signal Efficiency in Rural Areas through Variable Maximum Green Time

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  1. Improved Traffic Signal Efficiency in Rural Areas through the use of Variable Maximum Green Time Aswini Rajagopalan

  2. Outline • Introduction • Definitions • Work Done By Others • Research Plan • Site Selection and Description • Methodology • Results and Discussion • Conclusions and Recommendations

  3. Introduction: • Traffic Signal? • Why do we need it? • Where do we install it?

  4. Introduction (contd): • Working of a traffic signal: • Timers • What is being timed in a traffic signal? • Green • Yellow • Red

  5. Introduction

  6. Introduction Contd… Statistics • Researchers at Oak Ridge National Laboratory • 296 million vehicle hours of delay • 56% - poor traffic signal timings. • Updated Traffic Signal Timings • 10 to 40% reduction in delay, • 10% reduction in fuel consumption, • 22% reduction in harmful emissions

  7. Introduction Contd… • Modes of Traffic Signal Operation: • Pre-timed mode • Cycle lengths, phases, green times are all preset • Actuated mode • Green Time could be modified according to the demand. • Phase can be terminated in the absence of demand.

  8. What is the problem? “UNMET DEMAND”

  9. Definitions • Minimum Green Time • Vehicle Extension • Normal Maximum Green Time • Dynamic Maximum Green Time/Variable Maximum Green Time • Dynamic Maximum Step Size

  10. VMGT • Variable Maximum Green Time • variation of maximum green time in a step-wise manner • according to the traffic fluctuations (unmet demand), • within certain specified limits of green • in an actuated phase. • It is an additional feature of modern traffic controllers.

  11. Terminology (Operation of VMGT) • Gap Out • Max Out

  12. Variable Maximum Green Time • Picture taken from RESEARCH REPORT ON IMPROVING DIAMOND INTERCHANGE OPERATIONS USING ADVANCED CONTROLLER FEATURES By Engelbrecht et al(2001)

  13. My Study • Objectives: • Evaluate a generic set of VMGT parameters that can be used to reduce the delay and increase the throughput of an isolated intersection. • Methodology: • Software-in-the-Loop Simulation • Traffic simulation software - VISSIM

  14. Work Done by Others • Engel Brecht et al(2001) • Improving diamond interchange operations using Advanced Controller Features. • one among the eight features considered. • Adaptation to unexpected demand- positive results.

  15. Work Done by Others Contd… • Yun et al (2007) • evaluated the Adaptive Maximum feature in the EPAC300 actuated Traffic Controller. • Hardware-in-the-loop Simulation. • compared the VMGT with both a normally optimized maximum green and an arbitrarily large maximum green. • Result- VMGT performed better.

  16. Gaps in the Literature • Generic set of VMGT parameters • Yun- VMGT parameters based on site-specific optimized timing. • All phases • EngelBrecht - exit ramp phases on a diamond interchange. • 16-hour volumes • Yun- peak hour volumes

  17. Research Plan Data Collection Base Model Development Development of Timing Plans Simulation Data Reduction and Initial Strategy Development Multi Run Simulation and evaluation of results Conclusions and Recommendations

  18. Site Selection • Site selection criteria: • Isolated intersection • At a Rural area. • Presence of apparent queuing. • Difference in volume.

  19. Site description (Site 1) • Site 1 – NC 11 at NC 5, Pinehurst,NC • Speed Limit – • East-west -55 mph • North-south- 35 mph • ADT- 20000 vehicles

  20. Site description (Site 2) • Site 2 – Dixie at 9th,Cookeville, TN • Speed Limit- 15 mph • ADT- 20000 vehicles

  21. Site description (Site 3) • Site 3 – Willow at Jackson, Cookeville,TN • Speed Limits • East-West – 30 mph • North- South- 35 mph • ADT – 40,000 vehicles

  22. Methodology

  23. Different Timing Plans

  24. Different Timing Plans Contd… • Default Timing Plan • Optimized Timing Plan

  25. Different Timing Plans Contd… • VMGT Timing Plan

  26. Results and Discussion • Three performance measures: • Throughput Analysis • Delay Analysis • Signal Analysis

  27. Throughput Analysis – Site 1 • Throughput Analysis: • Can a signal using VMGT serve the same amount traffic as a signal using optimized timings?

  28. Throughput Analysis – Site 2

  29. Throughput Analysis – Site 3

  30. Delay Analysis – Site 1 • Can VMGT perform better than or equivalent to optimized treatment in terms of delay?

  31. Worst Approach and Worst Movement Delay – Site 1

  32. Delay Analysis – Site 2

  33. Worst Approach and Worst Movement Delay – Site 2

  34. Delay Analysis- Site 3

  35. Worst Approach and Worst Movement Delay – Site 3

  36. Signal Analysis • Whether VMGT was able to increase or decrease the green time according to the varying demand in a reasonable way? • In other words whether VMGT is able to provide reasonable cycle length? • Concern

  37. Signal Analysis

  38. Conclusions Contd… • Signal Analysis • Whether VMGT was able to increase or decrease the green time according to the varying demand in a reasonable way? – YES • In other words whether VMGT is able to provide reasonable cycle length? -YES

  39. Cycle Length- Site 1

  40. Signal Analysis- Site 3

  41. Conclusions • Throughput Analysis: • Can a signal using VMGT serve the same amount traffic as a signal using optimized timings? – YES • Delay Analysis: • Can VMGT perform better than or equivalent to optimized treatment in terms of delay? – YES • Site 1 - sharp AM peak • Site 3 - Existing↔VMGT • Sites 1and 2,VMGT = Optimized • Site 3, VMGT = best Intersection Worst approach/movement

  42. Recommendations • Generic VMGT parameters • Normal Maximum Green Time = 20 seconds • Dynamic Maximum Step Size = 10 seconds • Dynamic Maximum Green Time = 60 seconds • Controller settings: 2 (max outs and gap outs) • Detection is compulsory.

  43. Future Research • Proper methodology • Dynamic Maximum Green • Dynamic Step Size • Coordinated Actuated control. • Different Strategies with different Dynamic step sizes and Dynamic maximum could be tried. • For e.g. – from 10 to 15 secs for step for site 1.

  44. Acknowledgements • Advisor – Dr. Steven Click, Tennessee Technological University. • Vice President, CTE, Nashville – Jim Morinec • PTV America - Kiel Ova • Kim King , Marshall Boyd – CTE, Nashville

  45. Questions?

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