Activity-Based Model

An Activity-Based Model (ABM) is an advanced travel demand forecasting approach that simulates transportation choices by modeling the full daily activity patterns of a synthetic population of individual travelers and households. Unlike traditional four-step models that aggregate trips between zones, ABMs recognize that travel is derived from the need to participate in activities like work, school, shopping, and recreation, and that choices are interdependent within a person's daily schedule and household context. ABMs generate a synthetic population matching census demographics, assign activity schedules based on observed behavioral data, choose destinations and modes for each activity, and route resulting trips through the transportation networkTransportation NetworkA Transportation Network is the interconnected system of roads, railways, waterways, and transit routes that enables .... Microsimulation tracks each individual through their day, capturing complex behaviors like trip chaining, time-of-day choice, and intra-household vehicle allocation that aggregate models cannot represent. Applications include evaluation of congestion pricing policies where individual responses to tolling depend on trip purpose and schedule flexibility, transit investment analysis where mode choice varies by traveler demographics, land use scenario planning where activity locations shift with development patterns, and equity analysis that examines how transportation changes affect different population segments. Major metropolitan planning organizations including those in Los Angeles, San Francisco, and Atlanta have adopted ABMs for their enhanced policy sensitivity and behavioral realism.