5_J_Benson_TRB_presentation

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Published on December 4, 2008

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Development of Hurricane Rita Evacuation Trip Tables for the Houston-Galveston Region : TRB Planning Applications Conference Development of Hurricane Rita Evacuation Trip Tables for the Houston-Galveston Region Jim D. Benson, Texas Transportation Institute Chris Van Slyke, Houston-Galveston Area Council Alan C. Clark, Houston-Galveston Area Council Today’s Presentation : TRB Planning Applications Conference Today’s Presentation Dimensioning The Problem Study Area And Data Base Trip Generation Models Trip Distribution Models Time-of-day Factors Developing Alternative Scenarios Hurricane Rita – Sept 2005 : TRB Planning Applications Conference Hurricane Rita – Sept 2005 Evacuation Zones : TRB Planning Applications Conference Evacuation Zones Slide 5: TRB Planning Applications Conference Example Evacuation Speeds : TRB Planning Applications Conference Example Evacuation Speeds Morning 9/22 H-GAC Study Area : TRB Planning Applications Conference H-GAC Study Area Houston TranStar Rita Evacuation Survey : TRB Planning Applications Conference Houston TranStar Rita Evacuation Survey Solicited participation on website Participants responded to questions online 6,570 respondents 6,286 usable household responses 3,886 households evacuated by car or truck Evacuation Generation Models : TRB Planning Applications Conference Evacuation Generation Models Models developed for Rita event Structured to facilitate exploring different evacuation scenarios APPROACH : TRB Planning Applications Conference APPROACH Six-day event modeled Cross-classification variables: 6 geographical districts 5 household size groups Production models: Probability of evacuating Vehicle trips/evacuation household Trip purpose split Simple attraction models Non-resident trip models Six Districts : TRB Planning Applications Conference Six Districts Slide 12: TRB Planning Applications Conference Slide 13: TRB Planning Applications Conference Slide 14: TRB Planning Applications Conference Internal Evacuation Attractions : TRB Planning Applications Conference Internal Evacuation Attractions External Station Evacuation Attractions : TRB Planning Applications Conference External Station Evacuation Attractions Distributed attractions to other urban areas based on their population and relative accessibility Allocated results to external stations Rita Evacuation Generation Results : TRB Planning Applications Conference Rita Evacuation Generation Results Slide 18: TRB Planning Applications Conference Slide 19: TRB Planning Applications Conference Two Trip Distribution Models : TRB Planning Applications Conference Two Trip Distribution Models Evacuation trips to internal zones Evacuation trips to external stations Distribution Model For Internal Attractions : TRB Planning Applications Conference Distribution Model For Internal Attractions Essentially a “constrained interactance” model No friction factors No iterative process Constrained to productions Interaction constraint Productions allocated to eligible attraction zones based on relative attractiveness Interaction Constraint : TRB Planning Applications Conference Interaction Constraint No attractions to zones in the 3 mandatory evacuation areas Eligible attraction zones must be either: Further from the coast, OR 80+ miles from the coast Distribution Model For External Station Attractions : TRB Planning Applications Conference Distribution Model For External Station Attractions Similar to traditional external-local models Primary difference: external stations are treated the attractions Somewhat relaxed version of the normal external-local friction factors used TRIP DISTRIBUTION RESULTS : TRB Planning Applications Conference TRIP DISTRIBUTION RESULTS Time-of-day Factors : TRB Planning Applications Conference Time-of-day Factors Estimated from survey data Developed for each of the six districts Hourly Distribution for 6-day Event Slide 26: TRB Planning Applications Conference Slide 27: TRB Planning Applications Conference Developing Alternative Scenarios : TRB Planning Applications Conference Developing Alternative Scenarios Consider adjustments to % households evacuating by district Consider adjusting hourly distributions by district Consider adjusting vehicle trip rates to reflect taking fewer vehicles by district Questions? : TRB Planning Applications Conference Questions?

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