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NCTCOG And “Next Generation” Modeling Ken Cervenka, P.E., AICP North Central Texas Council Of Governments For AMPO Travel Modeling Work Group Meeting Kansas City, Missouri September 28, 2004
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Agenda Current Modeling Environment Multi-Year Network Coding Next Steps—Near Term Next Steps—Taking The Plunge
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Total Population Within The Dallas – Fort Worth Metropolitan Planning Area
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Four-Step Modeling Process TRIP GENERATION TRIP DISTRIBUTION MODE CHOICE ROADWAY ASSIGNMENT TRAVEL TIME CONVERGENC E TRANSIT ASSIGNMENT NO YES ZONE LAYER DEMOGRAPHIC INFORMATION ROADWAY NETWORK TRANSIT NETWORK LOOP ROADWAY SKIMS TRANSIT SKIMS INPUT PROCESS DECISION
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Market Segmentation To Account For Differences In Commuter Behavior Segmentation Basis (6 HBW And 6 HNW) –Household Income (3) Low Medium High –Vehicle Availability For A Household (2) Vehicles Less Than Persons Vehicles Greater Than Or Equal To Persons
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Traffic Assignment User Equilibrium Generalized Cost (Three 30-Iteration Assignments) A.M. Peak (6:30a – 8:59a: 2.5 hours) P.M. Peak (3:00p – 6:29p: 3.5 hours) OffPeak (18 hours) Four Vehicle Classes Loaded Simultaneously Drive Alone (Sees HOV-Toll Lanes As Tolled) Shared-Ride (Sees All HOV Lanes As Free) Shared-Ride (Doesn’t See Any HOV) Trucks (Vehicles With 6 Or More Tires)
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Multi-Year Network Concept One Link/Node Layer And One Transit Route Layer For ALL Years Contains ALL Streets Essentially A 25-Year TIP! Travel Model Network Extracted From All Streets Layer Link And Route Selections Based On Start And End Date Fields Local And Non-MPA Street Links Excluded
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Example: Blue Street Links Are Extracted To Travel Model Links
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Agency's "Master Roadway Layer" Covers 16-County NCTCOG Area
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2003 Digital Aerial Photos (Six Inch)
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Example: Future-Year Interchange
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Single-Point Intersection
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Network Coding Environment
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GIS Database Integration
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Some Tough Issues True Multi-Year Coding Is A Complex Environment But Allows For Greater Consistency/Quality Control Between Travel Model Years (And With TIP) Traffic Counts And Detailed Roadway Data (Including Traffic/Transit Projections): Should We Put Everything On the Web? Who Pays For The Initial Collection Costs? Is Everything Free To The End User? Should We Be Concerned About Possible Misuse?
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Taking The Plunge: Activity-Based (AB) Modeling Maybe It Is “Put Up Or Shut Up” Time! We Must Find Out Where Things Stand Rigorous Sensitivity Tests Of Estimated Models NCTCOG Can Test CEMDAP (UT-Austin/DFW Data) Other Agencies Can Test Other AB Model Brands Major Issues For Resolution: Current Worthiness And Readiness Of AB Models Spatial/Temporal Transferability Of Formulations/Estimations If Not Ready: Realistic Costs And Timeframes For Improvements
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Simple Sensitivity Tests (Examples) Global Increase/Decrease Of Input Variables Area-Specific Increase/Decrease Of Input Variables Check Local/Regional Change In Travel Patterns Check Local/Regional Change In Person Miles Perform Same Tests With Implemented Four-Step Model
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If Current Activity-Based Model Formulations/Estimations Aren’t Ready For The Real World: Form An MPO (Or MPO/DOT) Consortium Pooled Funding/Staff Resources Pooled Survey Data And Network Skims Identify Realistic Project Scope Competitive Procurement Of University/Consultant Team Independent Review Panel/Paid Workgroup Team Quarterly Meetings For Sponsors To Measure Progress Public Exposure May Help Keep Everyone Honest/Objective Must Deal With Proprietary Software Issues
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Desired Results For Pooled Funding Effort Applied Research Conducted In An Orderly Fashion Does A New Theory/Latest Fad “Smell” Right? Each Model Calibration/Validation Effort Builds Upon Successes/Failures Of Previous Implementations Provide Support For New Basic Research Discourage A Start-From-Scratch Mentality
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For E-Copy Of This Presentation Type In This URL: http://www.dfwinfo.com/trans/program_areas/travel_forecasting.html Or Simply Google On: “NCTCOG Travel Forecasting Program” And Look Under “Travel Forecasting Presentations”
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