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Xin (Alyx) Yu, E.I.T. University of Hawaii at Manoa Presented at the ITE Western District Annual Meeting June 25, 2012.

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Presentation on theme: "Xin (Alyx) Yu, E.I.T. University of Hawaii at Manoa Presented at the ITE Western District Annual Meeting June 25, 2012."— Presentation transcript:

1 Xin (Alyx) Yu, E.I.T. University of Hawaii at Manoa Presented at the ITE Western District Annual Meeting June 25, 2012

2 Outlines Problem Solution Application Conclusion

3 PROBLEM

4 Downstream Spillback Restricted upstream capacity Deteriorating downstream traffic conditions

5 Existing Approaches Traffic simulation/modeling Simtraffic VISSIM TransCAD EMME/2 Complex Algorithm Genetic algorithm (GA)-based Macroscopic hypothetical model

6 Weaknesses of Existing Methods Data-intensive or compute-intensive Expensive to gather the data Impractical for a project in the early stage of alternative screenings Impractical for a minor/temporary project with a limited budget

7 So we need…… A quick process to analyze downstream queuing effects Using the basic and typically available data Must be reliable and easy to use

8 SOLUTION

9 We have HCM…… Investigate capacity constraint of downstream queues by reversing and integrating the HCM procedures of intersection capacity and queue length estimation HCM 2010: f (X,Y) = Z f (Arrival Rate (X), Signal Timing (Y)) = Vehicle Queue Length (Z) Our method: f (Z,Y) = Y f (Max Allowable Queue Storage Length, Downstream Intersection Signal Timing) = Max Downstream Allowable Arrival Rate

10 Example: Is there queue spillback at EB downstream? Existing EB Downstream Entry Volume V.S. Max Downstream Allowable Arrival Rate. If less, no queue spillback and upstream capacity expansion is possible If greater or equal to, queue spillback will occur or is about to occur

11 Spreadsheet Tools Developed using Microsoft Excel 2007 A one page worksheet containing three sections: Inputs, Summary and Output. Download available at my personal website: (model tab)

12 APPLICATION

13 Vineyard Blvd. and Punchbowl St. Two capacity expansion options on the WB: 1. Underpass lane 2. At-grade lane

14 Analysis and Evaluation

15 Movements of Downstream Approach Determinant of Arrival Capacity Downstream Arrival Capacity (veh/hr) Existing Arrival Volume (veh/hr) Queue Spillback Occurred? Left TurnYES NO Through/Right TurnNO Upstream Treatments Downstream Arrival Capacity (veh/hr) Design Capacity (veh/hr) Maximum Additional Upstream Arrival Spillback Occurred? and Capacity Loss (veh/hr) Underpass Lane Yes, 990 At-grade Lane600630No, 0 Existing With Project

16 CONCLUSION

17 Conclusion This process can answer: 1. Spillback occurrence (when and where) 2. The feasibility of intersection treatments (considering intersection interactions) This process can be used in: 1. Project screening and planning level assessment 2. Developing a prioritized list of potential capacity expansion in urban corridor.

18 Questions and Comments Xin (Alyx) Yu, E.I.T. University of Hawaii at Manoa Personal Website: www2.hawaii.edu/~xinyu


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