1. 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

2. Outline Introduction Research Objective System Description
Analytical Model
Application

3. Introduction Demand-Responsive Feeder Transit (DRC)
Implemented in some cities, such as Denver
Service area: a demand-responsive operation
Major transit network

4. 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

5. 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
Terminal 1
Zone 1: Feeder line operations
Terminal 2
Zone 2: Feeder line operations W
Terminal 3
Zone 3: Feeder line operations
Point Z

6. 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

7. 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

8. 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

9. Thank You Very Much More detail in
Xiugang Li and Luca Quadrifoglio, “Optimal Zone Design for Feeder Transit Services.” TRB 88th Annual Meeting Compendium of Papers DVD (Paper ), or Transportation Research Record (in Press)
Thank You Very Much