TRB 2016 Blue Ribbon Committee
16th National Transportation Planning Applications Conference

Activity-Based Model Sensitivity Testing In The Baltimore Region – With Baby-Boomer Retirement, Who’S Filling The Jobs In The Future?

Corresponding Author: David Kurth, Cambridge Systematics, Inc.

Presented By: David Kurth, Cambridge Systematics, Inc.


Activity-based models (ABM) are designed to provide improved sensitivity to transportation system changes, policy testing, and traveler characteristics. One of the major demographic issues facing regions into the near- and medium-term future is the increase in retirement age population. ABMs along with population synthesis models allow for the investigation of the impacts of the increasing numbers of Baby Boomers reaching retirement age. Kim, et al., presented overall system results of such a test for the Atlanta region at the 2015 Transportation Planning Applications Conference.

A key assumption regarding ABMs is that they model traveler behavior not travel patterns. However, since most ABMs are estimated using cross-sectional travel survey data, a question regarding how reasonably the ABMs simulate changes in traveler behavior under different conditions. If a region continues to have economic growth with commensurate increases in employment as the population ages, the number of workers in the normal working ages of 18-65 may not keep pace with the number of jobs available. Does the ABM make up the difference by “making 70 the new 65,” does it fill available jobs with multiple part-time workers, or does it leave implied deficits in the numbers of jobs actually filled by workers.

This presentation investigates changes in the modeled travel behaviors of different age groups using InSITE, the recently developed ABM for the Baltimore Metropolitan Council. The study “instantaneously aged” the 2012 Baltimore region population to show a 30 percent increase in retirement age population. The presentation reviews not only absolute changes in travel components such as the numbers of daily activities and tours by type, but changes in rates by different population age groups. Behaviors of the base and aged population groups are compared for characteristics such as the average numbers of work tours per person, changes in work and non-work tours per person made by part- and full-time workers, and the times of day and durations of work tours. Different geographic areas and employment groups are also compared to determine the numbers of workers are adequate to fill available jobs.


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