This work has benefitted from continuous funding from such agencies as the National Science Foundation, the Federal Highway Administration, the California Department of Transportation, and the U.S. Department of Transportation's University Transportation Centers Program, as well as the support of private sector firms. Prior work has included: (a) the application of pattern recognition techniques to activity pattern classification; (b) the development of STARCHILD, the first operational activity-based model; (b) development of joint models of activity and travel demand using structural equations models; (d) microsimulation of activity patterns to produce dynamic origin-destination matrices; and (e) development of the Household Activity Pattern Problem (HAPP) Model. Current efforts include:

• REACT!
  REACT! is a computer-assisted, self-administered interview software for comprehensive travel surveys (24/7) of activities and activity-scheduling. Current applications include investigating the evolution of travel behavior following changes in residential location, and evaluation of a shared-use station car program (ZEVNET) with electric vehicles.

• TRACER
  TRACER is an integrated hardware/software project where a portable in-vehicle data logger was designed and build to track vehicles (using GPS and wireless communications) and GIS- and web-based software is being developed for both system monitoring and analysis. Applications include the ZEVNET project, the residential location project, and probe vehicle studies (more of a traffic application). TRACER and REACT! are being integrated.

• Agent-based Models
  CASA researchers are developing agent-based models of activity systems, with individual (traveler) agents negotiating with individual (land use) agents for activity performance. Related work includes the study of activity sequencing (also using TRACER) and activity scheduling (using REACT!)

• HAPP and Optimization Approaches
  These approaches utilize variations of OR techniques such as the pick-up and delivery problem with time windows to represent the execution of daily activity patterns (activity, destination, duration, and mode choices) within a household. Some environmental applications have been completed.

• Simulation Approaches
  Using activity patterns as more comprehensive version of trip typical generation rates, a Monte Carlo simulation for a population of synthetic households using GIS has shown very promising results.

• Empirical Approaches
  Development of structural equation models of activity behavior have led to the revision of trip generation approaches to reflect the influence of household interaction, vehicle mix and vehicle miles travelled, and other traveller characteristics. Other studies have considered impacts of land use patterns and designs on associated travel behavior and constraints.

• Interface of Conventional and Emerging Paradigms
  The interface between conventional and activity-based forecasting models, as well as the interface between "macro" forecasting models and traffic operations and analysis has been a recent research focus. The growth in traffic microsimulation models is much constrained by limited knowledge on the demand side as much as data restrictions on the supply side. UCI has several current projects in this area and has just established a Center for Traffic Simulation Studies. UCI's evolving research in the next generation of traffic simulation models is as great as its current interest in the next generation of travel forecasting models.