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Xin (Alyx) Yu, E.I.T. University of Hawaii at Manoa

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Presentation on theme: "Xin (Alyx) Yu, E.I.T. University of Hawaii at Manoa"— Presentation transcript:

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


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


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
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)


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 Analysis and Evaluation
Existing Movements of Downstream Approach Determinant of Arrival Capacity Downstream Arrival Capacity (veh/hr) Existing Arrival Volume (veh/hr) Queue Spillback Occurred? Left Turn YES 1830 1200 NO Through/Right Turn With Project Upstream Treatments Downstream Arrival Capacity (veh/hr) Design Capacity (veh/hr) Maximum Additional Upstream Arrival Spillback Occurred? and Capacity Loss (veh/hr) Underpass Lane 1830 1620 630 Yes, 990 At-grade Lane 600 No, 0


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:

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