Southern California Region

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
Heavy Duty Truck PCE Values by Vehicle Type,
Terrain and Percent Trucks
12.5
23
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.
24
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)
25
Regional Model Screenlines
26
Comparison of Truck Volumes and Counts on
Regional Model Screenlines
27
Subregional Corridor Screenlines
28
Comparison of Truck Volumes and Counts on
Subregional Screenlines
29
Comparison of Total Vehicular Volumes and Traffic
Counts on Regional Screelines
30
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

31
Comparison of 2020 and 1995 Forecast Truck
Volumes on Regional Model Screenlines
32
Regional Model Screenlines
33
Comparison of 2020 and 1995 Forecast Truck
Volumes on Regional Model Screenlines
34
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.