SUBWAY INUNDATION AND WHHELCHAIR
USER EVACUATION DURING TSUNAMI BY NANKAI TROUGH EARTHQUAKE
Yuhei SHODA,Taisuke ISHIGAKI and Tomohiro YASUDA
Graduated school of science and engineering,Kansai University
Kansai University, Environment and Applied systems Engineering
Introduction & Purpose◆◆◆

Japanese government issues that Nankai-Troughearthquake occurs within 30 years with 70% probability.
In urban area, there are subway line. It is assumed thatthese are likely to be inundated by water related disaster.
Wheelchair users need help by someone in the caseevacuate from subway.
The purpose of study is to investigate safe evacuation ofwheelchair users from subway in the case of tsunami
Fig.1 inundated subway ininundation.
Fukuoka by heavy rain ;MILTT

Study Area
Study area is Osaka city. Fig. 2 shows topography of Osaka city based on data issued
by Geospatial Information Authority of Japan. Ground elevation of the west side area
is below the mean sea-level . Osaka city is very vulnerable to tsunami inundation. Fig. 3
shows subway network in Osaka and station numbers.

Fig. 2 topography of Osaka city

Fig. 3 subway network in Osaka (Osaka Metro)

MethodIn this study, 2D shallow flow model was used. Cabinet office issued 11 tsunami modeland the four severe cases were investigated were calculated. Finest resolution oftopographic data is 30m. The water level of Osaka Bay is set T.P+1.20m in this study.
Levees of the simulation model are neither destroyed nor sank down. The overflow
discharge is calculated by using Honma's formula.

Result◆ Comparing the results of the four cases, resultof the case 10 shows the deepest and thelargest inundation area. Fig.4 shows Inundationarea and almost all of the west part of Osaka
city was inundated. According to the result, 16
subway stations were inundated.
◆ If the subway is flooded, it is difficult forhandicapped people to move in awheelchair. Thus, people must evacuatefrom underground space by the time whensubway station inundated. Fig.5 shows
timeline of evacuation. In this study, it ispresumed they decide to evacuate fromthere at stage 1 (110 minutes after the Fig.4 maximum inundation depth of study area
earthquake). The time between stage 1 andstage 3 is defined as lead time(LT). And,evacuation time of wheelchair users (EW)is
the time between stage 1 and stage 2. In thecase of earthquake, elevator is not available
Fig.5 Timeline of evacuation
so that people must use stairs. In this survey, ittakes a second for 4 people to climb a stepof stair with wheelchair and its users, andspeed of wheelchair is 0.5m/sec on the floorof subway stations in the case with assistant.
◆ Fig.6 shows LT and EW of inundated stations.LTof the N11, N13 and N23 station was only 9minutes. It was not enough for wheelchairusers to evacuate from these subway stations.
From the results, it is concluded that people
should evacuate from subway stations after
shaking of the earthquake finishes.
Fig.6 LT and EW of inundated stations

conclusion◆LT of several stations was not enough to evacuate for wheelchair users.
◆Thus, people should decide to evacuate from subway stations after the shaking ofmega earthquake finished.
◆In order to execute safe evacuation of people, station staff should be trained toguide people including wheelchair users and other disabled persons.

ReferenceKawanaka, R., Ishigaki T., Ozaki, T. and Toda, K. (2017), Safe Evacuation of Wheelchair Users from Underground Mall by Pluvial Flooding, Proceeding on the symposium on underground space ,22, 123-126. (in Japanese)
Terada, M., Okabe, R., Ishigaki, T., Ozaki, T. and Toda, K. (2016), Subway Inundation by Pluvial Flooding in Urbanized Area, Journal of Japan Society of Civil Engineer, Ser. B1(Hydraulic Engineering), Vol. 72, No.4, ppI_1357_I_1362. (in Japanese)