Development of a cost-optimized model for evacuation route planning for tsunamis

Abstract

This paper addresses the problem of planning inland evacuation routes along a given coastal stretch. This study presents a methodology to determine the optimum interval for proving inland evacuation routes within a stretch of vulnerable coastal area. It is evident that the developing countries may face financial constraints while providing necessary infrastructure facilities to minimize the fatalities. The establishment of evacuation routes or structures involves expensive capital and maintenance costs. Policymakers need a scientific basis to evaluate the provision of infrastructure facilities as part of planning emergency response strategies. The proposed methodology looks at the trade-off between the cost of providing infrastructure for evacuation and the cost of exposure to the risk. A total cost model is derived as the sum of infrastructure cost and cost of people being exposed to the risk as a function of uniform spacing between inland evacuation routes. The optimum uniform spacing that minimizes the total cost is derived. Thus, the spacing between evacuation routes is obtained as a function of the value of time saved from exposure to the risk, population density in the area, hazard zone depth, walking speed of individuals, and cost of infrastructure. Thus, the derived model is applied to a case study in Thelwaththa Grama Niladhari Division (GND), located in the southern province of Sri Lanka, which was severely affected by the 2004 tsunami event.