, pp.97-101 http://dx.doi.org/10.14257/astl.2015.100.21 Upward Evacuation Experiment for Estimating Evacuation Speed in Water Disaster Ji-Soo Lee 1, Won-Hwa Hong 2 1 Assistant Professor, Departments of Disaster Prevention and Safety, GyeongJu University, 188, Taejong-ro, Gyeongju-si, Gyeongsangbuk-do, 780-712, Korea, iris9972@naver.com 2 Professor, School of Architectural, Civil, Environmental and Energy Engineering, Kyungpook national Univ., 80, Daehak-ro, Buk-gu, Daegu, 702-701, Korea, Corresponding Author: hongwh@knu.ac.kr Abstract. Despite a principle of quick, upward evacuation in water-related disasters, a formula has not been produced that estimates evacuation speed by different slopes of evacuation paths. As a result, there is little engineering grounds to select a shelter site or decide service range of a shelter in case of a tsunami or a flood. In this study, evacuation simulations were conducted under a scenario of a water-related disaster. The simulation was designed to examine the declining evacuation speed by different slopes of evacuation paths and different ages of evacuees, assuming an upward evacuation to a higher ground. The results are expected to be useful for setting effective evacuation criteria or conducting future simulations. 30 people participated in the experiment, and a formula that estimates declining evacuation speed by slope of evacuation path was established that can be applied to the general public. Lastly, the maximum evacuation distance was estimated as well. The study results are expected to provide valuable data for objective information on water-related disasters. Keywords: Slowdown in Evacuation Speed, Possible Maximum Evacuation Distance, Water Disaster, Evacuation Experiment 1 Introduction As floods and other water-related disasters occur more frequently with climate change, many lives are lost every year. Studies are underway to seek both structural and nonstructural measures to reduce loss of lives. Among water-related disasters, tsunami and flood require evacuation to a safe place, and as such, the form and speed of evacuation, as well as the location and size of a shelter determine a successful evacuation. Nonetheless, criteria on physical properties of a shelter are non-existent that can be used to decide a location of shelter in consideration of people s walking speed and upward movement in evacuation. This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(msip) (No.2011-0030040) ISSN: 2287-1233 ASTL Copyright 2015 SERSC
Particularly, in case of an earthquake or a tsunami, having a guideline for quick evacuation would be the most effective way of reducing loss of lives, as they are hard to predict in advance. To do so, it is essential to develop a systematic method of measuring an actual evacuation time to a shelter and finding an adequate location of a shelter. In this study, we aim to develop a formula that estimates evacuation speed by different slopes of the evacuation path, to estimate an evacuation time to a shelter, in consideration of an upward movement to a higher ground in cases of water-related disasters. As for research methodology, potential shelter sites with different slopes were identified, and 30 subjects were selected by different age groups to conduct an evacuation simulation in a water-related disaster. Based on the simulation results, we established a formula to estimate evacuation speed by different slopes of evacuation path, and discussed how to use the data for geographic information based assessment of adequate shelter location. 2 Criteria to Choose Shelter in Water Disaster Generally speaking, there are two types of shelter: temporary shelter and designated shelter. A temporary shelter is used for temporary evacuation where people can move to quickly and secure safety in an emergency. In comparison, a designated shelter can accommodate evacuees living for the time being[1]. Many studies, including the standards for civil defense facilities in Korea, require an evacuation within 5 minutes after a tsunami takes place. Many studies use 5 minutes as a threshold to decide the service range of a shelter[2]. Given this, the following Equation 1 can be used to calculate the possible evacuation distance, to decide the location of a shelter. L = v (T-t1-t2) (1) In Equation 1, L represents a possible maximum evacuation distance, V, walking speed, T, estimated arrival time of earthquake/tsunami in a particular area, T1, time between the disaster and the beginning of evacuation, and T2, time taken to evacuate to a higher ground. In case of a water disaster or a tsunami, using vehicle is banned, and people should evacuate on foot. For this reason, a walking speed becomes a key variable in estimating the service range of a shelter. In a study to estimate walking speed (v), Bohannon[3] showed that adult men and women in their 20s through 70s had a usual walking speed of 1.27~1.46m/s, and 1.75~2.53m/s when they walked faster. Park [4] reported that, in case of a fire, slow walkers walked at 1m/s, fast walkers at 2m/s, and the standard speed was 1.33m/s. Yun et al.[5] conducted an evacuation simulation in a high-rise building, and reported that elderly people could descend the building at the maximum speed of 1.387m/s, and ascend the building at the maximum speed of 0.78m/s. However, earlier studies[6-9] examined walking speed in a normal condition or on the stairs, and thus hard to apply to disaster events, for the lack of consideration for an emergency situation. These results can be only limitedly applied to considering topo- 98 Copyright 2015 SERSC
graphical condition of shelter sites and estimating the consequent slowdown in walking speed due to a slope of the evacuation path. 3 Evacuation Experiment Design In case of water-related disaster, it is important to study evacuation of more vulnerable people like the elderly or the handicapped, but in this study, the research scope was limited to estimating evacuation speed on a slope. For experiment, 30 men and women between ages 15 and 60 were selected and divided into three groups which is commonly used in social science research and the results were compared and analyzed. Table 1 illustrates three groups of research. Table 1. Test subject group of the research Classification Age Range Number of person Male Female Total Group1 15~29 5 5 10 Group2 30~44 5 5 10 Group3 45~60 5 5 10 Total 15 15 30 Based on the principle of upward evacuation in a water disaster, four types of evacuation paths were assumed with an average slope of 0, 5, 10, and 15. To find experiment sites, Arc GIS was used to analyze slopes of sites, which was overlaid on road information, to find potential evacuation paths with average distance of 800m or longer. Fig. 1. Procedure of average slope Copyright 2015 SERSC 99
4 Experiment Results The test results show a significant difference in walking speed by age groups (Table 2). Participants in Group 1 had ages between 15 and 29, and it was estimated that they can walk 741m in five minutes on a flat surface. This compares to 540m for Group 3. On the steepest path (15 ), participants showed average walking speed of 1.54m/s, or 460m of evacuation distance in five minutes Table 2. Result of experiment Cours e 0 5 10 15 Group 1 2 3 4 5 6 7 8 9 10 AVG Group1 2.56 2.63 3.06 2.91 2.70 2.11 2.33 2.13 1.81 2.42 2.47 Group2 2.31 2.09 2.20 2.45 2.08 1.70 2.07 1.99 1.92 1.95 2.08 Group3 1.74 1.85 1.78 1.84 1.58 1.92 1.90 1.80 1.72 1.85 1.80 Group1 2.65 2.26 2.69 2.70 2.42 1.71 2.31 1.74 1.76 1.79 2.20 Group2 2.31 2.09 2.20 2.45 2.08 1.70 2.07 1.99 1.92 1.95 2.08 Group3 1.61 1.55 1.61 1.53 1.39 1.42 1.60 1.54 1.59 1.72 1.55 Group1 2.24 2.03 2.26 2.16 2.20 1.48 2.09 1.38 1.72 1.48 1.90 Group2 2.01 1.69 1.74 1.91 1.60 1.52 1.80 1.82 1.75 1.72 1.76 Group3 1.37 1.39 1.26 1.25 1.38 1.49 1.28 1.28 1.49 1.51 1.37 Group1 2.09 2.12 1.92 2.03 2.06 1.36 2.03 1.34 1.39 1.49 1.78 Group2 1.93 1.46 1.66 1.57 1.50 1.43 1.62 1.60 1.50 1.46 1.57 Group3 1.32 1.19 1.21 1.39 1.39 1.21 1.27 1.23 1.15 1.26 1.26 Unit : m/s 5 Conclusions The objective of this study is to estimate evacuees walking speed to decide service scope of an evacuation shelter, which has lacked engineering grounds until now. In case of water-related disasters like a flood or a tsunami, it is unavoidable that people move upward to a higher ground for evacuation, which makes it essential to have a declining speed coefficient in a formula by slopes of evacuation path. Nevertheless, few studies have been conducted to this end. Follow-up studies may be conducted on vulnerable evacuees such as elderly people, to produce a formula that considers evacuation speed of both vulnerable evacuees and others. 100 Copyright 2015 SERSC
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