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Optimal Zone Design for Feeder Transit Services. Xiugang Li and Luca Quadrifoglio Zachry Department of Civil Engineering Texas A&M University, College Station, TX Presented at the 12 th National Transportation Planning Applications Conference May 21, 2009 Houston, TX. Outline.
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Optimal Zone Design for Feeder Transit Services Xiugang Li and Luca Quadrifoglio Zachry Department of Civil Engineering Texas A&M University, College Station, TX Presented at the 12th National Transportation Planning Applications Conference May 21, 2009 Houston, TX
Outline • Introduction • Research Objective • System Description • Analytical Model • Application
Introduction • Demand-Responsive Feeder Transit (DRC) • Implemented in some cities, such as Denver • Service area: a demand-responsive operation • Major transit network
Research Objective • For large communities, planners may divide the whole service area into zones • A non-optimal structure often adopted • We developed a rigorous design methodology with analytical formulas
System Description • Service area divided into n zones • Within each zone, fixed-route transit (FRT) or demand-responsive transit (DRC) adopted • A fraction of customers move from the service area to the terminal Major L Transit Network Zone 1: Feeder line operations Terminal 1 Terminal 2 Zone 2: Feeder line operations W Terminal 3 Zone 3: Feeder line operations Point Z
Analytical Model • Total Cost Function • FRT Total Cost = Customer Cost + FRT Bus Cost • DRC Total Cost = Customer Cost + DRC Vehicle Cost • Customer Cost: waiting, walking, ride
Analytical Model • Optimal Number of Zones, n • FRT Total Cost f(n) is a convex function • DRC Total Cost p(n) is a convex function
Application • We applied the model to El Cenizo, Texas - one of the colonias, which are unincorporated settlements along the U.S. – Mexico border • With collected travel demand data, we determined optimal number of zones • One-zone design is the best for FRT policy • For DRC policy one-zone is best when demand<50; larger demand has more than one zone, but cost is larger than FRT policy; so choose one zone
More detail in Xiugang Li and Luca Quadrifoglio, “Optimal Zone Design for Feeder Transit Services.” TRB 88th Annual Meeting Compendium of Papers DVD (Paper 09-2608), or Transportation Research Record (in Press) Thank You Very Much