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Southern California Region Heavy Duty Truck Model

Southern California Region Heavy Duty Truck Model. Issues and Needs. Heavy Duty Truck Movements Important Element of Regional Planning 600 Million Annual Tons of Goods - 70% by Truck Trade, Transportation and Manufacturing 40% of Regional Employment

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Southern California Region Heavy Duty Truck Model

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  1. Southern California Region Heavy Duty Truck Model

  2. Issues and Needs • Heavy Duty Truck Movements Important Element of Regional Planning • 600 Million Annual Tons of Goods - 70% by Truck • Trade, Transportation and Manufacturing 40% of Regional Employment • 30% Growth in Goods Movement for Next 20 Years • Heavy Truck Movements in Many Regional Corridors • SCAG Model only Forecasts Light and Medium Duty Vehicles • HDT Movements Were Previously Estimated Only • Effects of Trucks on Traffic • Effects of Traffic on Trucks

  3. Purpose of the Project • HDT Travel Demand Modeling Capabilities for the Region • Forecast HDT Volumes and Patterns • Develop Direct HDT Emissions Analysis • Planning and Programming Regional Truck Improvements

  4. Model Objectives • State of the Art HDT Model • HDT Model Integrated with SCAG Model • Relationship with Goods Movement and Economic Activity • Readily Available and Forecastable Input Data • Stratification by Truck Types • Stratification by Trip Type - Long Haul, Short Haul • Dynamic Simultaneous Assignment Procedure • Effects of Trucks in Terms of Passenger Car Equivalents • Outputs: Volumes, VMT, VHT, Speeds, Travel Time, Congestion

  5. Project Components • Research and Data Collection • Model Component Development • Component Assembly and Incorporation with SCAG Model • Model Validation • Model Application and Forecasts

  6. Research and Data Collection • Over 70 Reports, Data Bases and Documents Reviewed • Very Few Regional Models Have Comprehensive HDT Component • Goods Movement Data Base • Carrier Surveys • Trip Diaries • Shipper and Receiver Surveys • Caltrans Truck Counts • New Classification Counts • Weigh-in-Motion Station Data • Freeway PCE Speed/Flow Surveys • Discussions with Subregions and COGs • Technical Advisory Committee

  7. Structure of the Model • Three Weight Categories by Gross Vehicle Weight (GVW) per ARB • Trip Generation for Internal Trips • Trip Distribution for Internal Trips • External Trips Generation and Distribution • Special Generators, Generation and Distribution • Time of Day Factoring • Traffic Assignment - Light-Heavy -- 8,500 to 14,000 GVW - Medium-Heavy -- 14,000 to 33,000 GVW - Heavy-Heavy -- Over 33,000 GVW

  8. HDT Model Structure

  9. Trip Generation for Internal Trips • Based on Shipper and Receiver Surveys • Telephone Surveys through Business Directory • Standard Industrial Classification Codes (SIC) - One Digit • Categories - Agricultural, Mining, Construction - Transportation and Communication - Wholesale Trade - Retail Trade - Services - Government - Households • Other National Truck Trip Rates • 988,700 Total Internal Trips - 45% LH - 33% MH - 22% HH • Major Generators: Retail, Manufacturing and Transportation

  10. Internal Trips

  11. Special Truck Trip Generators • Port of Los Angeles • Port of Long Beach • Intermodal Transfer Terminals • Air Cargo Trips at Regional Airports

  12. Total Trip Generation • 989,000 Internal • 36,000 External • 16,000 Port Trips • 10,000 Air Cargo Trips

  13. Trip Distribution • Gravity Model Format • Friction Factors by Weight Class • Truck Trip Diary Surveys • Based on Observed Trip Length Frequencies

  14. External Trips • Based on Commodity Flows • Southern California Goods Movement Study • County to County Movement of Goods by Tonnage - Truckload - Less-than Truckload - Private Carrier Tonnage Converted to Truck Trips by Class • Outbound Based on Producing Industries • Inbound Based on Consuming Industries • Disaggregated to Regional Zones Based on 2-Digit SIC • Allocated to Regional Model Cordon Points

  15. Time of Day Distribution • Daily Trip Generation • Distribution to Four Periods (AM, Midday, PM, Night-time) • Weigh-In-Motion (WIM) Station Data • Factors for Internal and External Truck Trips • Factors by Weight Class

  16. Heavy Duty Vehicle Classification Correspondence

  17. Heavy Duty Truck Time Period Distribution Factors (Percent of total daily 24-hour)

  18. Network Development • Network Capacity Re-Adjustments • Network Coding of Significant Grades • Truck Restrictions

  19. Traffic Assignment • Truck Assignment Integrated with Traditional Auto Assignment Process • Dynamic Two-way Interaction Between Autos and HDT During Assignment (Truck PCE Adjustments): - Significant Grades - Composition of Trucks - Level of Congestion

  20. HDT Traffic Assignment Process

  21. Heavy Duty Truck PCE Values by Vehicle Type, Terrain and Percent Trucks

  22. Percent Trucks Volume/ Light- Medium- Heavy- in Traffic Capacity Heavy Heavy Heavy <.5 0.6 0.7 0.9 0 -5 .5 -1 0.8 0.8 1.2 1 -1.5 1.1 1.2 1.3 1.5 -2 1.0 1.2 1.2 >2 1.0 1.2 1.3 <.5 0.7 0.8 0.9 5 -10 .5 -1 0.9 1.0 1.2 1 -1.5 1.2 1.3 1.3 1.5 -2 1.0 1.2 1.3 >2 1.0 1.2 1.3 <.5 0.7 0.8 0.9 >10 .5 -1 0.9 1.0 1.2 1 -1.5 1.2 1.3 1.3 PCE Value Adjustment Factors for Highway Congestion 1.5 -2 1.0 1.2 1.3 >2 1.0 1.2 1.3 Note: Numbers in this table are not PCE values. They are a djustment factors which should be applied to PCEs in previous table for each condition.

  23. Calibration/Validation • Model Calibration at Every Step • Assignment Validation - Total 11 Regional Screenlines - 1% Variance - Total 24 Sub-regional Screenlines - 8% Variance - Check for Reasonableness on Arterials (percent trucks between 4% and 7%)

  24. Regional Model Screenlines

  25. Comparison of Truck Volumes and Counts on Regional Model Screenlines

  26. Subregional Corridor Screenlines

  27. Comparison of Truck Volumes and Counts on Subregional Screenlines

  28. Comparison of Total Vehicular Volumes and Traffic Counts on Regional Screelines

  29. Products/Application • Provides Missing Component to the Existing SCAG Model • Forecast of HDT on Freeways, Arterials and Ramps • Forecast of HDT by Peak Periods and Classification • Forecast of HDT Speeds, Emissions, VMT, VHT, • O/D Trip Patterns, Local vs Through Trips, Facility Users

  30. Comparison of 2020 and 1995 Forecast Truck Volumes on Regional Model Screenlines

  31. Recent Improvements • New allocations of trucks to the four time periods (AM, PM, MD, and NT), based on driver survey. • New 2000 employment SIC data from EDD • Revised PCEs • New 24-hour truck counts • Removed K-factors in the original HDT model.

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