6 Weaknesses of Existing Methods Data-intensive or compute-intensiveExpensive to gather the dataImpractical for a project in the early stage of alternative screeningsImpractical 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 dataMust 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 estimationHCM 2010: f (X,Y) = Zf(Arrival Rate (X) , Signal Timing (Y)) = Vehicle Queue Length (Z)Our method: f (Z,Y) = Yf(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)
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 assessment2. 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