Simulation-based and risk-informed assessment of the effectiveness of tsunami evacuation routes using agent-based modeling: A case study of Seaside, Oregon

This study proposes a simulation-based and risk-informed framework for quantitative evaluation of the effectiveness of evacuation routes in reducing evacuation risk. Typically, tsunami evacuation routes are marked using signs in the transportation network and the evacuation map is made to educate people on how to follow the evacuation route. However, tsunami evacuation routes are usually identified without the support of evacuation simulation, and the route effectiveness in the reduction of evacuation risk is typically unknown quantitatively. An agent-based model is used to simulate the tsunami evacuation. The route effectiveness in reducing the evacuation risk is evaluated by investigating how the evacuation risk varies with the proportion of the evacuees that use the evacuation route. The impacts of critical risk factors such as evacuation mode (for example, on foot or by car) and population size and distribution on the route effectiveness are also investigated.

The results of the study shows that the overall evacuation route effectiveness in Seaside, Oregon is effective in reducing the evacuation risk. However, the evacuation risk would decrease less or even increase when most of the evacuees follow the route, especially under the relatively large population. Also, route usage is more effective in reducing the evacuation risk by car (that is, CCR) than the pedestrian evacuation risk (that is, PCR). However, it is important to note that as more people evacuate by car the overall evacuation risk (that is, TCR) also increases. The above results can be used to guide the improvement of the tsunami evacuation through preparedness education, for example, encouraging people to evacuate on foot instead of by car and follow the evacuation route. The car use could be discouraged by conducting the evacuation drill and following the evacuation route is encouraged by becoming familiar with the route (for example, reading the evacuation map).