Overview of Freight Framework

Overview of Freight Framework#

POLARIS freight ABM framework synthesizes and simulates freight agents and their interactions, with the goal of replicating their supply chain operations. The freight ABM framework consists of the Collaborative, Informed, Strategic Trade Agents with Logistics (CRISTAL) framework as the base of its simulation of business-to-business (B2B) operations, in addition to extra modules that model the external-external flows, empty trips, service operations, and business-to-consumer (B2C) e-commerce and on-demand deliveries (ODD).

Freight transport operations that are simulated in POLARIS:

  1. B2B operations for the freight intensive sector (FIS), i.e., sectors with generating physical goods are their main economic activity. These B2B operations are simulated through CRISTAL, an agent-based framework that synthesizes freight agents and simulates their B2B operations, a detailed description of the CRISTAL model and the major differences compared to other agent-based models can be found in the references at the bottom of this page. CRISTAL models firms’ strategic decisions in selecting their suppliers and carriers. Using those formed long terms partnerships, logistical decisions are modeled by estimating the mode and shipment information, which is used to optimize and route delivery tours.

  2. External-External (EE) freight loaded and empty trips are simulated using data from Freight Analysis Framework (FAF). The national freight flows are disaggregated into county level flows which are then assigned to the national network. Given the known origin-destination of the flows, the internal-external (IE), external-internal (EI), and EE trips of a given study region are extracted and calibrated with their associated empty trips against the Highway Performance Monitoring System (HPMS) traffic counts on the major highways at the region boundary.

  3. Service operations, including the demand modeling of maintenance visits to households and businesses, and the simulation of their associated tours.

  4. B2C operations, including E-Commerce and ODD operations. Building on the population synthesis integrated in POLARIS, each household demand is estimated for online ordered packages, meals, and groceries. The packages are handled by delivery trucks that perform deliveries to households through delivery tours starting from fulfillment centers. The meals and groceries are handled by the TNC modules to simulate their deliveries through ridesharing.

All these models are calibrated to match the target values within the study region. Additionally, freight trips that are not generated in POLARIS, are sourced from the total metropolitan planning organizations’ (MPO) freight trips. These trips are then fed into simulation directly to capture a full picture of all the freight trips within the study region. Details of freight modeling components developed in Polaris are as below figure.

Polaris-freight components

The whole models and procedures are developed as Polaris Freight ABM model as below. The framework covers from firm synthesis and channel choice models to logistics formulation and daily truck operations, which is simulated on Polaris network with other passenger travels.

Polaris-freight structure

Important

Please refer to the the following papers for more details:

Stinson, M., and A. (Kouros) Mohammadian. Introducing CRISTAL: A Model of Collaborative, Informed, Strategic Trade Agents with Logistics. Transportation Research Interdisciplinary Perspectives, Vol. 13, 2022, p. 100539. https://doi.org/10.1016/j.trip.2022.100539.

Stinson, M., J. Auld, and A. (Kouros) Mohammadian. A Large-Scale, Agent-Based Simulation of Metropolitan Freight Movements with Passenger and Freight Market Interactions. Procedia Computer Science, Vol. 170, 2020, pp. 771–778. https://doi.org/10.1016/j.procs.2020.03.157.