  Integrating land use, travel demand, and traffic models represents a gold
standard for regional planning, but is rarely achieved in a meaningful way,
especially at the scale of disaggregate data. In this paper, we present a new
architecture for modular microsimulation of urban land use, travel demand, and
traffic assignment. UrbanSim is an open-source microsimulation platform used by
metropolitan planning organizations worldwide for modeling the growth and
development of cities over long (~30 year) time horizons. ActivitySim is an
agent-based modeling platform that produces synthetic origin-destination travel
demand data, developed from the UrbanSim model and software framework. For
traffic assignment, we have integrated two approaches. The first is a static
user equilibrium approach that is used as a benchmark. The second is a traffic
microsimulation approach that we have highly parallelized to run on a GPU in
order to enable full-model microsimulation of agents through the entire
modeling workflow. This paper introduces this research agenda, describes this
project's achievements so far in developing this modular platform, and outlines
further research.
