Influence of road network and population demand assumptions in evacuation modeling for distant tsunamis

Natural Hazards
By: , and 

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Abstract

Tsunami evacuation planning in coastal communities is typically focused on local events where at-risk individuals must move on foot in a matter of minutes to safety. Less attention has been placed on distant tsunamis, where evacuations unfold over several hours, are often dominated by vehicle use and are managed by public safety officials. Traditional traffic simulation models focus on estimating clearance times but often overlook the influence of varying population demand, alternative modes, background traffic, shadow evacuation, and traffic management alternatives. These factors are especially important for island communities with limited egress options to safety. We use the coastal community of Balboa Island, California (USA), as a case study to explore the range of potential clearance times prior to wave arrival for a distant tsunami scenario. We use a first-in–first-out queuing simulation environment to estimate variations in clearance times, given varying assumptions of the evacuating population (demand) and the road network over which they evacuate (supply). Results suggest clearance times are less than wave arrival times for a distant tsunami, except when we assume maximum vehicle usage for residents, employees, and tourists for a weekend scenario. A two-lane bridge to the mainland was the primary traffic bottleneck, thereby minimizing the effect of departure times, shadow evacuations, background traffic, boat-based evacuations, and traffic light timing on overall community clearance time. Reducing vehicular demand generally reduced clearance time, whereas improvements to road capacity had mixed results. Finally, failure to recognize non-residential employee and tourist populations in the vehicle demand substantially underestimated clearance time.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Influence of road network and population demand assumptions in evacuation modeling for distant tsunamis
Series title Natural Hazards
DOI 10.1007/s11069-016-2655-8
Volume 85
Issue 3
Year Published 2017
Language English
Publisher Springer
Contributing office(s) Western Geographic Science Center
Description 23 p.
First page 1665
Last page 1687
Country United States
State California
City Balboa Island