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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. DOWNSTREAM QUEUES ON UPSTREAM CAPACITY EXPANSION at URBAN SIGNALIZED INTERSECTIONS. Outlines. Problem Solution Application Conclusion. PROBLEM.
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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 DOWNSTREAM QUEUES ON UPSTREAM CAPACITY EXPANSION at URBAN SIGNALIZED INTERSECTIONS
Outlines • Problem • Solution • Application • Conclusion
Downstream Spillback • Restricted upstream capacity • Deteriorating downstream traffic conditions
Existing Approaches • Traffic simulation/modeling • Simtraffic • VISSIM • TransCAD • EMME/2 • Complex Algorithm • Genetic algorithm (GA)-based • Macroscopic hypothetical model
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
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
We have HCM…… • Investigate capacity constraint of downstream queues by reversing and integratingthe 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
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
Spreadsheet Tools • Developed using Microsoft Excel 2007 • A one page worksheet containing three sections: Inputs, Summary and Output. Download available at my personal website: http://www2.hawaii.edu/~xinyu (model tab)
Vineyard Blvd. and Punchbowl St. • Two capacity expansion options on the WB: 1. Underpass lane 2. At-grade lane
Analysis and Evaluation Existing With Project
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.
Questions and Comments Xin (Alyx) Yu, E.I.T. University of Hawaii at Manoa Email: xinyu@hawaii.edu Personal Website: www2.hawaii.edu/~xinyu