Heavy-Duty Truck Model

Heavy Duty Truck Model Thumbnail Image
Primary Purpose

Southern California Association of Governments (SCAG) developed the Heavy Duty Truck (HDT) Model to evaluate important policy choices and investment decisions. The HDT model is a primary analysis tool to support the goods movement policy decisions made by SCAG and regional stakeholders.

About SCAG’s HDT

As part of 2012-2035 Regional Transportation Plan/Sustainable Communities Strategy (RTP/SCS), the HDT model focused on analytical needs to support project and policy planning in the following key areas:

  1. Port Access Improvements

  2. Clean Technology Truck Lanes

  3. Freight Facility Developments and Land Use Strategies for Goods Movement-Oriented Activity Centers (Inland Ports, Freight Villages, new inland warehouse, and distribution center locations)

  4. Air Quality/Conformity Analysis

  5. Economic Impact Analysis

  6. Operational Strategies (port and highway)

The model development process included a thorough review of the HDT model by an expert panel that ranged from academics to Consultants. The HDT model was validated by comparing the overall vehicle miles traveled (VMT) for individual counties and air basins against the data obtained from the Highway Performance Monitoring System (HPMS).

Click on the Features and Framework of SCAG’s HDT Flow Chart for additional information.

FURTHER Information

The model documentation includes further information on the following topics:

  • HDT Model Structure: The model forecasts trips for three HDT weight classes: light-heavy (8,500 to 14,000 lbs. gross vehicle weight (GVW); medium-heavy (14,001 to 33,000 lbs. GVW); and heavy-heavy (>33,000 lbs. GVW

  • Internal HDT Model Development: This includes the development of all HDT trips that have both origins and destinations within the six-county modeling area.

  • Port Model Development: This includes the port model development that predicts the HDT trips coming out of and going into the San Pedro ports, which includes the Port of Long Beach (POLB) and Port of Los Angeles (POLA).

  • External HDT Model Development: This includes how the external HDT trips are captured in the HDT model that come into, go out of, and pass through the region.

  • Intermodal Trip Tables: This includes how the intermodal trip tables were derived and integrated with the HDT model.

  • Time-of-day Choice: This includes the derivation of time of day factors from various sources.

  • HDT Model Calibration and Validation: This includes validation data, procedures and results from various performance measures.

Documentation & Resources

Heavy Duty Truck Model Documentation

SCAG’s Goods Movement Program seeks to optimize the region’s transportation system through increases in economic efficiency, congestion mitigation, safety and air quality improvements, and enhancements to system security. In doing so, all modes of freight are being evaluated, ultimately resulting in a series of new recommendations and policies regarding infrastructure improvements.