14.2.3 Freight

This section focuses on truck freight and does not discuss rail, pipeline, air, and maritime freight.
Though typically a component of various facility analyses, truck freight does not typically receive a standalone analysis. If a standalone freight analysis is necessary (e.g., analysis of a truck freight-only facility), microsimulation is used.
Freight impacts operational analysis of many facilities because trucks have different characteristics than passenger cars (e.g., acceleration and deceleration rates, size, weight-to-power ratio, etc.). Some characteristics of freight that are considered when conducting an operational analysis are as follows:
  • Passenger car equivalency;
    • Certain analysis methods found in the HCM use a passenger car equivalency factor that converts truck traffic to passenger traffic for analysis
    • Microsimulation does not use a passenger car equivalency factor. It uses truck traffic counts or percentages
  • Truck traffic percentage;
    • This includes historical truck traffic percentages and projected truck traffic percentages
    • Adjusting truck percentage in a microsimulation (microscopic) model will account for truck characteristic variation
  • Origins and destinations of truck traffic; and
  • Interactions between truck freight and passenger cars
    • Truck freight characteristics are to be embedded in microsimulation, but default values may need to be changed
PCE values are found in the Basic Freeway and Multilane Highway Segments Chapter of the HCM 7th Edition. For level terrain, HCM 7th Edition defines the truck PCE as 2.0; for rolling terrain, the truck PCE is 3.0. In addition to the basic PCE values, HCM 7th Edition Exhibits 12-26, 12-27, and 12- 28 have PCE values for grade and truck composition (i.e., single-unit trucks and tractor-trailers) variations.
There are several resources that can be used to determine truck traffic percentage and other truck-related statistics:
  • Classification counts to determine truck traffic percentage can be obtained from permanent count stations or temporary counts stations on the TxDOT’s Traffic Count Database System (TCDS) application.
  • Weigh-in-Motion (WIM) stations are an important source of truck classification and weight data.
  • Transearch is a database tool that aggregates historical truck traffic and projects freight flows up to 30 years into the future. Freight information can be filtered by origin, destination, commodity, and transportation mode. It has county-level freight-movement data. Transearch is produced by IHS Markit. The data is classified by:
    • Inbound, outbound, intrastate, and through traffic;
    • Tonnage and value; o Commodity type; and
    • TxDOT TPP has a contract with the company that oversees the software (IHS Markit). Coordinate with the TxDOT Project Manager regarding the User License Agreement to access Transearch data
  • Some MPOs may have an OD dashboard that can be used for freight analysis
  • MPO TDM outputs.
  • SAM Freight Assignment Module:
     The SAM freight model includes a zonal structure that is specific to the freight components of the SAM. It defines freight zones based upon aggregated counts outside of Texas and counties within Texas. Freight tonnage is forecasted on an annual basis (annual tonnage) based on Transearch data. After the mode choice step, freight truck annual tonnage at the county level is converted to daily truck trips to be assigned to the roadway network. This tool can be used to obtain freight tonnage by origin and destination, the routing of tonnage carried by the mode, the commodity type of tonnage moving in the state, and the truck volumes on modeled roadways. MPOs also have TDMs that can be used to analyze freight
  • The FHWA and Bureau of Transportation Statistics (BTS) have created the FAF tool that outlines general freight movement between major metropolitan areas within Texas, from Texas to other states, and from Texas to Mexico and Canada. Freight information can be filtered by flow type, year, origin, destination, commodity, and distance. This tool has an emphasis on historical truck data and can be used for projects that involve historical traffic data.
Origin and destination data is used to determine the routes used by truck freight. This helps prioritize facility improvements and can also be used in microsimulation. Origin and destination data is often collected by using third-party probe data such as INRIX, Replica, Wejo, or StreetLight.
For more information on data collection that relates to freight analysis, see
Chapter 2
 in this manual.
  • TxDOT is developing the Truck Congestion Analysis Tool (TCAT) that is used as a Planning tool for analyzing and monitoring truck mobility. The tool provides mobility performance measures for major roads in Texas from 2017 to the present. The key features of this tool are found in .
Table 14-34: Truck Congestion Analysis Tool Key Features
Feature
Overview
Traditional mobility performance measures
Traditional mobility performance measures such as annual delay, delay per mile, congestion cost, travel time index, planning time index, and others are included in this tool.
Analysis levels
The TCAT includes information on the top 100 congested roadways and primarily focuses on the top 100 most congested roadways for trucks. TCAT also provides users the more comprehensive Roadway-Highway Inventory Network (RHiNo) which gives a more detailed picture at individual roadway segments, custom corridors, or regional summaries.
Performance summaries
The TCAT performance summaries presents results at various levels, including individual roadway segments, custom generated corridors defined by start and end points, regional areas, or pre-defined corridors.
Projects
The TCAT provides visualization layers for near-term and long-term transportation projects from the UTP and provide more information regarding the projects through the TxDOT Data Portal.
Annual Truck Congestion Report Cards
The TCAT provides a link to the Annual Truck Congestion Report Cards for each of the top 100 Truck Congested Roadways, as well as each of the pre-defined regions/geographies. The report cards help quickly examine performance trends.