Transportation Network Evacuation Planning with Household Activity Interactions

Abstract

An evacuation model that explicitly accounts for observed household interactions is presented. A series of linear integer programs determines household decisions of where its members will meet and how to organize the meeting logistics in the event of an evacuation. In the first mathematical program, the household selects a meeting location. In the second, the household members without vehicles are assigned to drivers. This second formulation results in an activity chain for each driver. These chains are then loaded onto the network using a microassignment simulation procedure that captures the resulting traffic interactions taking place in the network. An example is presented to illustrate the methodology; a network serving three business, six residential, and five school zones is examined. An evacuation during business hours is simulated using the activity chains for 20,000 households. Comparison of clearance times with different network loading strategies reveals that a minimum of 150% of the original demand should be used for evacuation planning purposes if no special considerations or adjustments to the network model are made. Modifying the network to account for unusual parking circumstances that may arise when parents pick up their children at school under emergency conditions may allow for a reduction in the amount of demand required for evacuation planning. The exact multiplicative factor depends on the loading scenario employed by the planning agency and any additional special emergency considerations that may be taken into account.