Charting Urban Travelers 24–7 for Disaster Evacuation and Homeland Security

Abstract

Major shifts in urban regions’ population distribution occur throughout the 24-hour day and the seven-day week. On weekday mornings, the population of residential zones declines and the population of educational, commercial, and employment zones increases. Weekday evening hours see a reverse of this pattern. The differences of population distribution throughout the urban region, especially the differences between night and day distributions, are extreme in most cities, and, therefore, of great importance to a variety of public officials, including transportation planners, highway patrol, and public service officials. The location of resident (night) population is documented through the U.S. census of population. Local metropolitan planning organizations (MPOs) usually update such statistics for their own purposes at least every five years. On a typical weekday between the hours of 7 a.m. and 7 p.m., most people are not at home, but have relocated themselves elsewhere in the urban region for a variety of activities. Zonal counts are required for 24–7 disaster preparedness. No such methods exist to target 24–7 population concentra-tions until now. The approach employed here provides ninety-five percent accurate zonal population counts across the urban region for each hour of the day and for each day of the week based on dynamic trip generation and trip distribution models and a GIS.