6Weaknesses 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
7So we need…… A quick process to analyze downstream queuing effects Using the basic and typically available dataMust be reliable and easy to use
9We 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
10Example: 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
11Spreadsheet 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)
17Conclusion 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.
18Questions and Comments Xin (Alyx) Yu, E.I.T. University of Hawaii at Manoa Personal Website: www2.hawaii.edu/~xinyu