Homeland security applications require fine modeling and simulation resolution in time and space to represent human activity and travel behavior. For example, key bridges might be identified as "critical" in terms of their importance to national security, economic activity, and public safety. Or, large sports stadiums, shopping malls, and office towers might be considered more of a substantial target when they are in use, but not when they are empty. The TRansporation ANalysis SIMulation System (TRANSIMS-LANL), an activity-based transportation modeling system, has the ability to simulate the movements of individuals around a network on a second-by-second basis between parcel-level locations. At the core of TRANSIMS-LANL are "synthetic" schedules (computer produced time allocations of individuals and households to activity such as work, leisure, and travel) which are formulated based on activity/travel diaries. All activity-based simulations like TRANSIMS-LANL require an immense amount of data to depict a specific city's population movements. The data are usually collected using activity/travel diaries in which respondents report all their activities over the span of a few days. While cities or small regions conduct their own surveys every seven to ten years, it is very time consuming to go out and collect data and prepare them for modeling. In order to model cities or large regions in a timely manner, a new methodology is needed that will allow a person's activity patterns to be "transferred" to another person living in a different geographic location. In this study, a methodology will be developed to transfer activity patterns from a national-level travel survey to a synthetic population at a local level. This will be accomplished by focusing on land use and accessibility. Existing and new accessibility and land form measures will be identified and applied along with socio-demographic variables for the respondents of a national travel survey to build a Structural Equation Model (SEM).
At the core of this research are questions about the connection between travel behavior and land use, land form, and accessibility that will be explored to determine what link, if any, exists. This connection is essential to establish when designing a process for the transferability of activity or travel patterns. The study has potential benefits for a wide cross-section of operational and research applications. All types of surveys, ranging from travel-related to those that access a person's health, are costly and time-consuming to administer. The ability to utilize surveys from one or more regions to construct a valid survey that immediately allows research or modeling to move forward will save thousands of dollars in cost and person-time. This methodology can be applied in all areas that require a spatial dimension in planning and operations/management, from health care to housing and urban development, from tax contribution calculations to traffic congestion and air quality. Within transportation, the purpose of designing a process to enable the transferability of activity or travel surveys from one region to another is to aid in the development of activity-based transportation models.
