Travel Demand Modeling At NCTCOG

Transcription

1 Travel Demand Modeling At NCTCOG Arash Mirzaei North Central Texas Council Of Governments For University of Texas at Arlington ITE Student Chapter March 9, 2005

2 Agenda Background DFW Regional Model Structure TxDOT Statewide Analysis Model Multi-Year Network Coding Example Projects Activity-Based Modeling

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4 Total Population Within The Dallas Fort Worth Metropolitan Planning Area 10,000,000 9,000,000 8,000,000 7,952,070 (New Plan) 8,503,146 7,000,000 6,000,000 5,000,000 4,848,237 5,650,339 6,671,351 (Previous Plan) 4,000,000 4,536,010 3,000,000 2,000,000 1,000, Previous Plan Demographics (Mobility 2025 Update) New Plan Demographics (Mobility 2025, 2004 Update)

5 NCTCOG Departments (9) Executive Director s Office Agency Administration Community Services Emergency Preparedness Environment And Development Public Affairs Research And Information Resources Transportation (Also Serves As The MPO) Workforce Development

6 Transportation Department Program Areas (6) Administration Air Quality Planning And Operations Information Systems Strategic Initiatives And Community Outreach Transportation Planning Transportation Programming And Operations

7 Information Systems Transportation Data Management (Including Web-Based Activities And GIS Support) Vehicle Operations (e.g., Traffic Simulation) Development, Maintenance, And Support Of Travel Demand Forecasting Tools

8 Modeling Environment NCTCOG-Developed FORTRAN Programs (Mainframe) MOBILE5A Emissions Analysis Latest Mobility Plan Update (Last Year) For Legacy Applications TRANPLAN (PC) Subarea Traffic Modeling (Legacy Applications) TransCAD (PC-Windows) MOBILE6 Emissions Analysis Future 2030 Mobility Plan All New Travel Modeling Activities

9 Key Decision #1: Software Selection We Are Tired Of Maintaining/Updating Our Own FORTRAN Programs It s Difficult, Being Our Own Software Vendor! And It Costs A Lot Of Money To Rent Mainframe Time Competitive Travel Model Software Procurement Process RFP Sent To Travel Model Software Vendors (1998) Selection Committee NCTCOG, Texas DOT, DART, And City of Fort Worth Staff TransCAD Selected From The Five Submissions

10 Key Decision #2: Should We Convert Our Existing Travel Modeling Procedures To TransCAD? Or Do We Use TransCAD For A Brand New Round Of Full Model Estimations And Calibrations?

11 Answer: Since We Had New Data: 1994 Workplace Survey 1994 External Travel Survey 1996 Household Survey 1996 and 1998 Transit Onboard Surveys 1994 and 1999 Major Traffic Count Programs But Our Current Models Were Calibrated From 1984 Survey Data It Was Time To Perform New Model Development (But Start With Our Existing Roadway And Transit Networks)

12 Key Decision #3: Who Will Do The New TransCAD Model Development? Consultants Or NCTCOG Staff? We Did The Work In-House (But Cambridge Systematics Did The Mode Choice Estimations)

13 Travel Demand Forecasting Process Urban Activity Trip Frequency Destination Choice Mode Choice Roadway Route Choice Transit Route Choice

14 Four-Step TransCAD Modeling Process DEMOGRAPHIC INFORMATION ZONE LAYER ROADWAY NETWORK TRIP GENERATION ROADWAY SKIMS TRIP DISTRIBUTION TRANSIT NETWORK LOOP MODE CHOICE TRANSIT SKIMS ROADWAY ASSIGNMENT NO TRAVEL TIME CONVERGENCE YES INPUT PROCESS TRANSIT ASSIGNMENT DECISION

15 The Practicality Of Real-World Modeling Actual Scope Of Human Behavior Model Scope All Person Trips Motorized Person Trips All Travel Purposes HBW, HNW, NHB, And Truck Purpose Categories All Occupations Basic, Retail, And Service Jobs All Households Income And Household Size Categories (Plus Auto Ownership Breakdowns) All Streets Non-Local Streets Individual Data Aggregate Data (Zones)

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17 Creation Of 4,874-Zone Structure Start With Year 2000 Census Block Layer Ground Truth Rectification Some Block Splits (e.g., DFW And Love Field Airport) 76,336 Blocks Aggregated to 6,399 zones Add 61 External Station Tiny Circle Zones = 6,460 Total Zones Aggregate The 6,460-Zone Layer = 4,813 Internal Zones + 61 External Station Zones = 4,874 TransCAD Model Zones

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19 TransCAD Model Size 4874 Zones Retained For ALL Modeling Steps From Trip Generation To Traffic/Transit Assignment 4813 Internal + 61 External Number Of Zone-To-Zone Pairs = 23.8 Million Year 2025: 27,000 Roadway Links + 9,600 Zone Connectors Over 36,600 Coded Links 22,000 Network Nodes 2025 Transit 410 Coded One-Way Bus Lines And 36 Rail Lines 14,500 Bus Stops And 171 Rail Stations

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22 Single-PC Model Run Times (For 3.2 GHz Pentium PC) Full No Feedback Model Run = 647 Minutes (10.8 Hours) Trip Generation = 1.0 minute Roadway Skimming (4) = 11 minutes Trip Distribution = 11 minutes Market Segmentation = 6 minutes Transit Prep And Skimming (4) = 77 minutes Mode Choice (13) = 65 minutes Matrix Preparations (For Transit Assignment) = 10 minutes Transit Assignment (4) = 21 minutes Matrix Preparations (For Traffic Assignment) = 98 minutes Traffic Assignment (3) = 347 minutes (5.8 hours)

23 AUTOMATED NETWORK CONVERSION

24 Roadway Preparation Link Free Speed Based On Speed Limit, Distance, Area Type, Functional Class, And Intersection Control Directional Hourly Capacity Based On Lanes, Area Type, Functional Class, And Divided/Undivided Designation Time Period Capacity AM Peak, PM Peak, And OffPeak

25 Trip Generation GISDK Macro Language Seven Regular Internal-Internal Trip Purposes 4 HBW, 1 HNW, 1 NHB, And 1 Truck Inputs Population, Households, Median Household Income Basic, Retail, And Service Jobs (From SIC Codes) Special Generators (Shopping Malls, Colleges, Hospitals, Airports)

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29 What Is A Trip Production And A Trip Attraction? TRIP = Use Of Motorized Transportation (Auto, Motorcycle, Truck, Or Public Transit) For At Least A Portion Of The Journey Between Two Activities Home to Work = Home-Based Work (HBW) trip; Home is both Origin and Production end, while Work is both Destination and Attraction end Work to Home = Also a HBW trip; Work is both Origin and Attraction end, while Home is both Destination and Production end Nonhome to Nonhome = Nonhome-Based (NHB) trip; first activity of a NHB trip is always the Origin and Production end, while the second activity is always the Destination and Attraction end

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31 Trip Production Rate Table for HBW Inc.Q. Household Size

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33 External Station Trip Tables Internal-External And External-Internal (IE/EI) Weekday Passenger Vehicles (Total Trip Ends) External-External (EE) Weekday Passenger Vehicles IE/EI Weekday Trucks (Six Or More Tires) EE Weekday Trucks (Six Or More Tires)

34 TRIP GENERATION LIMITATIONS Calibrated Trip Rates Represent Survey-Based Averages A low-income, two-person household in Frisco has the same number of HNW trip productions as a low-income, two-person household in downtown Dallas A suburban furniture store with 50 retail employees (jobs) has the same number of HNW attractions as a suburban grocery store with 50 retail employees Trip Rates Are Not Impacted By Changes In Accessibility Trip rates remain fixed, regardless of changes in roadway travel times or accessibility to transit

35 Trip Distribution Gamma-Format Gravity Model (7 Purposes) Four HBW Groups (Income Quartiles) AM Peak Skims HNW (Non-Airport) -- OffPeak NHB (Non-Airport) -- OffPeak Trucks (Vehicles With Six Or More Tires) -- OffPeak Base Year Trip Table Factoring (6 Purposes) HNW And NHB Airport Trips Four External-Related Auto/Truck Trips

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38 Zone To Zone Skim Tables For Mode Choice Four AM Peak Skims (6:30a 8:59a) Roadway Without HOV Links Available (Drive Alone) Roadway With HOV Links Available (Shared Ride 2 And 3+) Transit Drive Access (PA Format) Transit Walk Access (PA Format) Four OffPeak Skims Roadway Is 18-hour Offpeak Without HOV Links Available (Drive Alone) With HOV Links Available (Shared Ride 2 And 3+) Transit Is 6-hour Mid-Day Offpeak (9:00a 2:59p) Drive Access (PA Format) Walk Access (PA Format)

39 Auto Travel Roadway Travel Time Roadway Length (Operating Cost) Daily Parking Cost Mode Choice Inputs Transit Travel In-Vehicle Transit Travel Time (Includes Dwell) Walk (Or Drive) Access Time Walk Transfer And Egress Time Initial And Transfer Wait Time Transit Fare Market Segment And Area Type Constants

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41 HBW Mode Choice: Mainframe vs. TRANSCAD Choice Drive Alone Shared Ride 3+ Shared Ride 2 Transit Drive Transit Walk Choice Auto Transit Drive Transit Walk Drive Alone Shared Ride 2 Shared Ride 3+

42 HNW Mode Choice: Mainframe vs. TRANSCAD Choice Drive Alone Shared Ride 2+ Transit Drive Transit Walk Choice Drive Alone Shared Ride Transit Drive Shared Ride 2 Shared Ride 3+ Transit Drive Transit Walk

43 NHB Mode Choice: Mainframe vs. TRANSCAD Choice Drive Alone Shared Ride 2+ Transit Drive Transit Walk Choice Drive Alone Shared Ride 3+ Shared Ride 2 Transit Drive Transit Walk

44 Post-Processing Of Link Speeds Example: AM Peak Directional Link Speeds Allocate (Based on Observed Time-Of-Day Factors) The 2.5-Hour AM Peak Assignment Volume Into Three Sub-Periods 6:30a 6:59a (30 Minutes) 7:00a 7:59a (60 Minutes) 8:00a 9:00a (60 Minutes) Calculate V/C ratios For Each Sub-Period Note: Capacity for 30-minute period is ½ the hourly capacity Apply The Post Process Volume Delay Curves

45 Some Traffic Model Issues To Keep In Mind Peak Spreading Of Trips Is Not Directly Modeled We Can Model HOV-Toll (Managed HOV) Facilities But Local Validation Data Doesn t Exist Since There IS Offpeak Congestion, We May Need Future Traffic Assignment Breakdowns Into Mid-Day (9:00 a.m. 2:59 p.m.) and Evening/Night (6:30 p.m. to 6:29 a.m.) Periods

46 Validation (Transit Slide 1) Observed vs Modeled Similarities in Peak and Offpeak Transit Speeds Used In Skimming for Mode Choice Model-Derived vs. Actual Bus and Train VMT for the Peak and Offpeak periods Modeled vs. Observed Weekday Riders by Bus Route and Rail Route (Route-Level RMSE and Percent Error) Modeled vs Observed Weekday Riders by Route Groups (e.g., by Quadrants or Radial Corridors)

47 Validation (Transit Slide 2) Modeled vs. Observed Weekday Rail Station Boardings (Station- Level RMSE and Percent Error) Reasonableness Of Modeled vs. Observed Mode of Access Distributions to Individual Rail Stations Sensitivity (Elasticity) Checks of Calibrated Model Parameters

48 Validation (Traffic--Slide 1) Current And Future-Year Reasonableness Of Roadway Speeds Used In Skimming For Trip Distribution And Mode Choice Reasonableness Of Modeled vs. Observed Percent Intrazonal Trips By Trip Purpose (DFW = 1.5% For HBW; 8.7% For HNW; 9.3% For NHB; And 0.5% For Trucks) Reasonableness Of Modeled vs. Observed Average Person Trip Lengths (Or Trip Length Frequency Distributions) By Trip Purpose, For Interzonal Trips Modeled vs. Observed Weekday Link Volumes By Functional Class (RMSE And Percent Error)

49 Validation (Traffic Slide 2) Modeled vs. Observed Weekday Screenline Volumes (Overall Magnitude And % Error); DFW = 1262 Links On 89 Screenlines Modeled vs. Observed AM Peak, PM Peak, And OffPeak Auto And Truck VMT By Functional Class (% Error) Check Very High And Very Low AM, PM, And OffPeak V/C Ratios Checks Of The Hundred Largest Link Errors Report Magnitude And % Error

50 Model Outputs: Supply-Side Calculations Number Of Coded Transit Lines Roadway Network Links (Or Miles) With Transit Total Physical Stops And Line Stops How Many Are Rail Stations How Many Are Transit Park-And-Ride Locations AM Peak And Mid-Day OffPeak Vehicle Miles And Hours Of Travel Population And Employment Within Buffer Areas

51 Direct Model Outputs Person Trip (Production-Attraction) Matrices (4874 x 4874) By Trip Purpose And Mode Of Travel Roadway And Transit Skim Matrices (4874 x 4874) ONs And OFFs (Boardings And Alightings) For Each Coded Transit Stop Transit Link Flow File (Stop To Stop) Movements File (Line To Line Rider Transfers) Link-Level Traffic Volumes And Speeds By Vehicle Class and Time Of Day

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