Exploratory Advanced Research . . . Next Generation Transportation Solutions

Integrated Urban Systems Modeling 

Designing a Seamless, Comprehensive Approach to Transportation Planning

New tour- and activity-based models of 

travel demand simulate the choices of travel 

times, modes, and routes and the impact they 

have on travel patterns. Travel demand models 

based on these concepts are in use or under 

development by several metropolitan planning 

organizations around the country.

Advanced transportation network modeling 

methods, such as dynamic traffic assignment, 

are used by a broad set of practitioners to inform 

project evaluation and operational planning, city 

roadway reconfigurations, design and evaluation 

of intelligent transportation systems, and estimating both typical and evacuation traffic. 

Any effort to integrate these three distinct 

arenas of microsimulation must draw on leaders 

in each area. “An innovative feature of this project,” says Brian Gardner, FHWA, “is the partnership among three research universities working 

together to integrate land use, travel demand, 

and transport network simulations, each providing leadership in its area of expertise.” Researchers at the Arizona State University, Tempe, are 

leading the activity–travel behavior modeling 

aspect of the study; a team from the University of 

Arizona, Tucson, is providing expertise in dynamic traffic assignment modeling; and scientists at 

the University of Washington, Seattle, are the 

project’s specialists in land-use microsimulation 

modeling and computational algorithms. Assisting the universities in the 3-year effort are the 

Arizona Department of Transportation, Maricopa 

Association of Governments and Maricopa County Department of Transportation in Phoenix, Pima 

Association of Governments in Tucson, and Puget 

Sound Regional Council in Seattle.

Key Challenges to Integrated Modeling

The microsimulation systems represent great 

differences in geographic and temporal scale, 

data structures, behavioral units and agents, 

and other characteristics. To reconcile these differences, the project team faces daunting tasks.

•	 Developing a robust framework, a “universal”

context, that allows true integration—not a 

mere linkage—of the dimensions.

The Exploratory Advanced Research Program Fact Sheet

Microsimulation of Urban Systems

The goal of this EAR project is not to devise new 

modeling software but to develop a conceptual 

framework, an integrated prototype, and computational tools with which others can tailor their 

own integrated systems, using available microsimulation models. These models cover a broad 

array of decisions and behaviors on the part of 

individuals, businesses, and governments, from 

long-term location choices to daily travel route 

choices.

Land-use modeling enables planners to simulate the interrelationships of land-use dynamics, 

transportation, and air quality, including feedback effects such as potential induced demand. 

UrbanSim, for example, is helping planners address 

policy issues related to reducing urban sprawl, 

altering travel behavior, and providing affordable housing. 

Metropolitan planning agencies face 

increasingly complex issues in modeling interactions between the built environment and multimodal transportation 

systems. Although great strides have 

been made in simulating land use, travel 

demand, and traffic flow, gaining the 

ability to model urban systems across 

these phenomena would be a revolutionary advance. This challenge is the focus 

of “Modeling the Urban Continuum in an 

Integrated Framework: Location Choice, 

Activity Travel Behavior, and Dynamic 

Traffic Patterns,” an Exploratory Advanced 

Research (EAR) Program project launched 

by the Federal Highway Administration 

(FHWA) in 2008.
•	 Resolving disparities in the treatment of time

and space.

•	 Defining units of analysis that facilitate consistency across models.

•	 Accommodating both highway and transit

components within multimodal systems.

In addition, because each of the microsimulation 

methods alone requires intensive use of computation resources, an important task of the research 

team is developing data structures and data 

handling systems for large complex databases 

so as to optimize computational performance, 

prevent data overload, and achieve reasonable 

run times. 

Progress

Initial information sharing among the research 

groups has been completed, the model architecture has been drafted, and a select external 

technical panel has been chartered to discuss 

the project direction. Panel review of the initial 

architecture is underway. 

Future Efforts

Upon completion, the prototype system will 

undergo real-world demonstration, modeling 

various network supply and socioeconomic, 

land use, and transport policy scenarios for an 

urban area with at least 1 million inhabitants and 

1,000 traffic analysis zones. Procedures for calibrating and validating the system to local areas 

will be developed. 

The researchers are committed to sharing 

knowledge through open-source applications, 

and the entire set of research products—source 

code, graphical user interfaces, programs and 

scripts, architecture documentation, and user 

guides—will be available at the project Web site 

for others to use and enhance. Project completion is anticipated in 2011.

The innovations achieved in this EAR effort 

are expected to have a major impact on 

transportation planning for sustainable futures. 

What Is the Exploratory 

Advanced Research Program?

FHWA’s Exploratory Advanced Research 

(EAR) Program focuses on long-term, 

high-risk research with a high payoff 

potential. The program addresses underlying gaps faced by applied highway 

research programs, anticipates emerging issues with national implications, and 

reflects broad transportation industry 

goals and objectives. 

To learn more about the EAR Program, visit the Exploratory Advanced 

Research Web site at www.fhwa.dot.gov/

advancedresearch. The site features information on research solicitations, updates 

on ongoing research, links to published 

materials, summaries of past EAR Program events, and details on upcoming 

events. For additional information, contact 

David Kuehn at FHWA, 202-493-3414 

(email: david.kuehn@fhwa.dot.gov), or 

Terry Halkyard at FHWA, 202-493-3467 

(email: terry.halkyard@fhwa.dot.gov).

Integrated Urban Systems Modeling 

Designing a Seamless, Comprehensive Approach to Transportation Planning

“In addition to a state-of-the-art integrated 

prototype,” says Gardner, “this effort will provide valuable lessons for next-generation 

transport modeling as well as direction for 

transport simulation frameworks.”

Learn More

For more information on this EAR Program 

project, contact Brian Gardner, FHWA Office 

of Planning, at 202-366-4061 (email: brian.

gardner@dot.gov).

Publication No. FHWA-HRT-09-042

HRTM-04/05-09(1M)