Model of Household Trip-Chain Sequencing in Emergency Evacuation

An evacuation modeling framework that bridges the gap between observed household behavior and traditional evacuation models is presented. Numerous observers have noted that household members seek each other and then evacuate as a single unit. The desire to find relatives before leaving an area may result in people moving toward the danger instead of away from it. This pattern has not been captured by traditional evacuation models, which assume that people immediately move away from the danger. The gap between observed behavior and theoretical models leads to longer-than-expected evacuation times. A series of two linear integer programs provide an expression for the household behavior in evacuation conditions. The first formulation determines the meeting location for the household members. The second formulation determines which drivers pick up each of the family members and the sequence of the collection. Tying these linear programs to traffic simulation software allows for a more complete evacuation simulation. Furthermore, information supply strategies may be incorporated into the simulation. The effect of information on reassignment and resequencing may also be examined.