Silviase/jgov_v1.4_full_ann huggingface dataset:
Fig.7 Total heat release rate in the various heat sources (wood, styrene foam)

どの火源の場合でも、3階居室の方が4階居室よりもCO濃度が高くなるが、CO濃度は3階居室と4階居室で同じオーダーで同程度であると言える。ただし、この場合は3階居室と4階居室を比較した場合であり、発泡スチロールの場合は木材に比べて3階居室では6.8倍程度、4階居室では8.5倍程度の高濃度のCOが存在する。

Fig.7は各種火源の発熱速度Qの時間変化を示す。ここで示す発熱速度QはFDSの入力データとして与えた(1)式の発熱速度Qではなく、計算過程での局所的な酸素消費量から求めた局所的な発熱速度の総和である。時刻t=240sまで、種々の火源の場合において発熱速度Qは上昇していく。木材の場合は時刻t=240s以降、平均的に発熱速度Q=1,700kW前後を推移するが、時刻t=500sで突然Q=2,900kWまで急上昇し、時刻t=1,200sでQ=1,400kW程度まで緩やかに減少する分布となった。また、発泡スチロールの場合は時刻t=240s以降、Q=1,600kW前後で平均的に一定になるが、時刻t=800sで緩やかに上昇し、時刻t=1,200sで発熱速度Q=2,400kW（平均）となる。Fig.7に示す発熱速度Qは(1)式に示す発熱速度Qを全体的に下回るが、これは局所的な酸素濃度の低減により発熱速度Qが低減されていることが反映されている。

3.2 火源位置の違いによる熱気流の変化と共通性

ここでは火源を発泡スチロールとし、火源位置

Fig.8 Contours of temperature and CO concentration at t=300s and t=900s by styrene foam fire (Heat source position II)

をFig.3に示すように火源位置Ⅰ及び火源位置Ⅱとして、それら火源位置の違いによる熱気流の変化と共通性を考察する。その際、3階居室入り口(3FLA（Fig.2）)は計算開始時から開放している。Fig.8は火源位置Ⅱの場合の時刻t=300s及び900sでのy2平面における温度分布及びCO濃度分布である。Fig.8と火源位置Ⅰの場合のFig.5（b）及びFig.6（b）を比較すると、温度分布に関しては火源位置が変わるため、階段室に多少の分布差は見られるものの、3階及び4階居室の温度分布には違いが認められない。また、火源位置Ⅱの場合においても1階及び2階の階段室と居室は計算開始から初期温度20℃のままで温度変化はない。CO濃度分布に関しては、時刻t=900sで3階居室のCO濃度がc3、c4点（Fig.4）で5,160ppm、3,040ppmとなり、Table 3を見ると火源位置Ⅰの場合の同点で4,460ppm、4,000ppmであるから、火源位置Ⅱの場合は3階居室のCO濃度が16%上昇し、3階及び4階居室のCO濃度差が大きくなるのがわかる。原因として、火源位置Ⅱは火源位置Ⅰに比べて火源
Fig.9 Total heat release rate in Styrene foam

の設置位置が3階居室入り口に近いために、熱気流が3階居室に流れやすくなり、3階居室のCO濃度が高くなったものと考えられる。また、3階及び4階居室において時刻t=300sでは層状分布であるが、時刻t=900sでは一様分布になり、火源位置Ⅰの場合と同じである。

Fig.9は火源が発泡スチロールの場合における発熱速度Qの時間変化で、火源位置ⅠとⅡの場合の比較である。火源位置Ⅱの場合は時刻t=240sまでかけて発熱速度Qが増加し時刻t=1,200sまで平均的に発熱速度Q=2,100kW前後で一定になる。火源位置Ⅰの場合と比べると火源位置の違いで発熱速度Qの時間変化の傾向が変わるのがわかる。

### 3.3 3階居室入りロドアの開放開始時刻と熱気流の関係

出火（計算開始）後、時刻t=60s、120s、180s、240s、300s経過した後に閉ざされていた3階居室入りロドア（3FL-A（Fig.2））を開放した。それが熱気流に与える影響を調べた。ここで、火源は発泡スチロールとし、設置位置は火源位置Ⅱ（Fig.3）とした。

Fig.10は出火（計算開始）から時刻t=0s（計算開始時から開放）、60s、120s、180s、240s、300s経過した後に3階居室入り口ドアを開放した場合の階段室（a3、a4、a5点（Fig.4））における温度の時間変化である。まず、ドア開放時刻t=0s及び60sの時の温度変化（Fig.10（a）、（b））は同じ傾向を示す。a4点（4階床面高さ）、a5点（屋上床面高さ）での温度は時刻t=240sまで発熱速度Qに対応して増加し、その後、a4点ではおよそ230℃、a5点ではおよそ130℃で一定となる。Fig.8（a）で示したように時刻t=300sと900sで温度分布の時間変化がないのが、このFig.10（a）からもわかる。a3点では大きな温度変化は見られなかった。次に、ドア開放時刻t=120sの時の温度変化（Fig.10（c））を見ると、時刻t=120sまで3階居室入り口ドアが閉塞されているため、建物入り口を除き階段室は密閉されることにより、a4、a5点では時刻t=120s付近でわずかな温度上昇が見られる。この場合もa3点では大きな温度変化は見られなかった。ドア開放時刻t=180sの時の温度変化（Fig.10（d））を見ると、ドア開放時刻t=120sの場合（Fig.10（c））と同様にa4、a5点では時刻t=180s付近で若干の温度の上昇が見られる。注目すべきこととしてa3点での温度が時刻t=120sから急上昇し時刻t=180sまで330℃になる。これは閉塞した階段室の上方にたまった熱気流が行き場所がなくa3点まで下がってきたことが原因である。3階居室ドアを開放した時刻t=180s以後は急激にもとの20℃付近にまで温度が下がる。ドア開放時刻t=240sの時の温度変化（Fig.10（e））を見ると、a3、a4、a5点ではそれぞれ680℃、580℃、200℃までの急激な温度上昇が時刻t=250sまで見られ、ドア開放時刻t=240sからおよそ10s程度時間遅れがある。ドア開放時刻t=300sの時の温度変化（Fig.10（f））を見ると、a3、a4、a5点でドア開放時刻t=240sの時と同様の温度まで温度上昇し、それが時刻t=320sまで続いた。ドア開放時刻t=300sを考えると時間遅れはおよそ20sである。

Fig.11はFig.10と同様に3階居室入りロドアを種々の時間経過後開放した場合の3階及び4階居室中央のb3、b4点での温度の時間変化である。b1、b2点は閉塞された1階及び2階居室内の参照点であるから温度変化はない。階段室で見られたような激しい温度変化は見られず、3階居室入りロドアを開放した時刻から3階居室中央温度であるb3点の温度がどの開放時刻の場合でも130℃程度まで上昇する。
Fig.12はFig.10の条件と同じ場合のCO濃度の時間変化である。ドア開放時刻t=0s、60s、120sの時のCO濃度変化（Fig.12（a）、（b）、（c））は同じで、a4、a5点でのCO濃度は出火時から時々刻々と増加していき、時刻t=1,200sでCO濃度は4,000ppmになるがそれ以降も増加するものと考えられる。a3点のCO濃度変化は温度変化と同様に見られなかった。ドア開放時刻t=180sの時のCO濃度変化（Fig.12（d））を見ると、a3点でのCO濃度が時刻t=120～200sで急激に増加しまた減少する。その時のCO濃度は2,500ppm程度である。ドア開放時刻t=240sの時のCO濃度変化（Fig.12（e））を見ると、時刻t=120～270sでa3、a4、a5点でのCO濃度変化が増加するが、特にa3、a4点のCO濃度は急激に増加しピーク時で5,000ppmである。ドア開放時刻t=300sの時のCO濃度変化（Fig.12（f））でも同様に時刻t=120～340sでa3、a4、a5点でのCO濃度が増加し、a3、a4点のCO濃度はピーク時で5,000ppmとなる。

Fig.13は3階及び4階居室であるb3、b4点でのCO濃度の時間変化である。b1、b2点は1、2階の居室が密閉状態であるため、CO濃度の時間変化は当然ない。b3点では3階居室入り口ドアを開放するまでCO濃度が上がることはないが、開放されるまでの間、4階居室であるb4点のCO濃度が増加する。例えば、Fig.13(a)では時刻t=300sの時の700ppmであるが、Fig.13(f)では同じ時刻で1,500ppmであり、およそ2倍程度のCO濃度の増加が見られる。ただし、3階居室入り口ドアを開放した後にはCO濃度はどの開放時刻の場合においても同程度となる。

### 3.4 3階及び4階居室での見透し距離について

Fig.14は階段室での見透し距離Dの時間変化である。ここで、見透し距離Dとは減光係数 $ C_{s} $ と定数Cを用いた $ D=C/C_{s} $ である。反射板形標識及び扉については定数C=2～4が用いられ、FDSでは定数C=3としている。FDSでは減光係数 $ C_{s}=K_{m}\rho y s $ として求める。ここで、定数 $ K_{m} $ はFDSでは木材やプラスチックを燃やした時を想定して $ K_{m}=7,600m^{2}/kg $ を既定値としている。 $ \rho y s $ はすす密度であり計算過程で得られる量である。限界見透し距離 $ D_{c} $ は建物内部を熟知した人で $ D_{c}=5m $ 、よく知らない人で $ D_{c}=30m $ とされている $ ^{[10]} $ 。本来、見透し距離Dは居室の空間平均見透し距離により評価するのが適当であると考えられるが、計算コストの都合から参照点であるa4、a5点での見透し距離Dを評価した。Fig.14から、a4、a5点の順で視界が悪くなり、限界見透し距離 $ D_{c}=30m $ を基準とした場合、Fig.14(f)では、a4、a5点の順でそれぞれ出火後時刻t=14s、55s後には視界が不良になる。a3点では熱気流の揺らぎが大きく、特に3階居室入りロドアを開放した後にその傾向が強くなる。この原因は以下のようである。3階居室入りロドアを閉塞している時には階段室の2階床面高さまで煙層が降りて来るが、3階居室入りロドアを開放すると、流れが3階居室に押し寄せ、階段室の煙層が3階床面付近にまで上昇する。ちょうどその煙層の境目に大きな変動が観測されるa3点があり、さらにその点が火源付近にあるために大きく揺らぐのである。

Fig.15は各階居室の見透し距離Dの時間変化である。3階居室入りロドアを開放すると同時にb3点での視界が不良になることがわかる。また、3階居室入りロドアを閉塞しておくと4階居室の視界不良が早まりFig.15（c）、（d）、（e）、（f）の場合にはb4点で出火後時刻t=100sで視界不良になることがわかる。

### 4. 結論

小規模建物階段室火災における熱気流の数値シミュレーションを、火源である可燃物の種類を変えた場合や閉塞した3階居室入りロドアを時刻t=0s、60s、120s、180s、240s、300sで開放した場合などの条件のもとに行い、以下の知見を得た。

(1) 火源位置Ⅰで3階居室入りロドアが常に開放の場合、火源からの熱気流は直接3階居室に流れ込み、次いで階段を経路として上昇した熱気流が4階居室に流れ込む。時刻t=900sの時、3階居室温度は100℃前後、4階居室温度は50℃前後であり、3階及び4階居室の一酸化炭素濃度は同程度である。
(2) 火源を発泡スチロールとし、火源位置Ⅰ、Ⅱの場合を比較したところ、3階居室入り口に近い火源位置Ⅱの場合では火源位置Ⅰの場合に比べて3階居室の一酸化炭素濃度が16%増加し、火源位置が3階居室の一酸化炭素濃度に影響を与えることがわかった。

(3) 3階居室入りロドアを閉塞しておくことにより、階段室上方に熱気流が溜まりやすくなり、降下した熱気流が4階居室に流れ込む。3階居室入りロドアを開放した時には熱気流は3階居室にも流れ込むが、その時までに階段室の一酸化炭素濃度は最大5,000ppmと高濃度状態になる。

(4) 見透し距離の観点から、4階居室の視界不良もまた3階居室入りロドアの開放時刻に大きく依存しており、温度や一酸化炭素濃度から見てもドア開放時刻が3階及び4階居室の熱気流の動きを支配する要因になっていると言える。

## 謝 辞

本研究の数値シミュレーションで用いた計算コードであるUNIX版Fire Dynamics Simulator（FDS）は米国商務省国立標準技術研究所（NIST）のMcGrattan博士により提供していただいた。ここに記して謝意を表します。

## 参考文献

1）総務省消防庁小規模雑居ビル火災緊急対策検討委員会：“新宿歌舞伎町ビル火災概要”，小規模雑居ビルの防火安全対策検討報告書(2001)

2）URL http://fire.nist.gov/

3) Smagorinsky, J.: “General circulative experiments with the primitive equations; Part 1. The basic experiment”, Monthly Weather Review, 91-3, pp.99-164 (1963)

4) Mell, W.E., McGrattan, K.B. and Baum, H.R.: "Numerical Simulation of Combustion in Fire Plumes", 26th Symposium (International) on Combustion, pp.1523-1530 (1996)

5) McGrattan, K.B., Baum, H.R., Rehm, R.G.,

Hamins, A., Forney, G.P., Floyd, J.E. and Hostikka, S.: "Fire Dynamics Simulator (Version 2) - Technical Reference Guide", National Institute of Standards and Technology. NISTIR 6783, pp.8-10 (2001)

6) McGrattan, K.B., Forney, G.P., Floyd, J.E. and Hostikka, S.: “Fire Dynamics Simulator (Version 2) - User’s Guide”, National Institute of Standards and Technology, NISTIR 6784, pp.19-21 (2001)

7）朴南燮，小林敏雄，谷口伸行：“チャンネル内立方体障害物周辺の流れのLESとQUICKの影響について”，第10回数値流体力学シンポジウム講演論文集，pp.172-173（1996）

8）日本建築学会防火委員会火災性状小委員会火災性状データベースWG：“日本建築学会・2001年度大会（関東）緊急ワークショップ「新宿雑居ビル火災に学ぶ」”，（資料4）新宿区歌舞伎町雑居ビル火災（9/1）ダイヤグラム(2001)

9）日本火災学会火災誌編集小委員会：“新宿・歌舞伎町明星56ビル火災”，日本火災学会誌Vol.51 No.5，pp.5-11（2001）

10）安全工学協会編：“安全工学講座1 火災”，pp.165-166，海文堂出版（1983）
# Numerical Simulation of Thermal Flow in a Small-Scale Building Staircase Fire

(Abstract)

Nobuyuki Abe, Tokiyoshi Yamada, Eiji Yanai, Takeshi Suzuki and Ai Sekizawa

(Received February 5, 2002)

The Shinjuku Myoujou building fire broke out on September 1, 2001. Forty-four people were killed in this fire. The main causes of the death seem to be carbon monoxide poisoning. The authors thought that it was important to know a smoke movement of this fire when considering future measure against fire fighting and evacuation, and performed CFD analysis of a small-scale building staircase fire that modeled this fire. The simulation from the time of outbreak of fire to 1,200 seconds was performed by using Fire Dynamics Simulator developed by NIST. As a result, when the third floor sitting room entrance door is opened, a thermal flow goes into the third floor sitting room and it also goes into the fourth floor sitting room gradually. When the third floor sitting room entrance door is closed, a thermal flow goes into the fourth floor sitting room after accumulating in the top of the staircase, and then goes into the third floor sitting room with opening the door at specific time. Therefore, open time of the third floor sitting room entrance door is a key factor that determines the motion of the thermal flow.
# Development of an Information System for Support of Fire-Fighting Activities in a Large Scale Disaster

Shinsaku Zama, Masafumi Hosokawa, Ken Hatayama, Makoto Endo, Yoshiyuki Matsubara, Hiroyuki Tamura, Ai Sekizawa, and Ken'ichi Takanashi

(Received February 5, 2002)

To enable an initial response to be conducted smoothly in case of a large-scale disaster, it is necessary to collect accurate disaster information immediately and transmit it to decision-makers such as the fire service headquarters. It is also important to create useful information based on the disaster information and a database such as water availability, hazardous material facilities, fire brigades and so on, and to disseminate such information to personnel in stricken areas. We have therefore developed a handy-type collection terminal, a digital communication system free from congestion, and real-time earthquake damage estimation system and fire-spreading simulation system. By integrating these elements and information technology, we have constructed a prototype system that supports effective initial response activities just after an earthquake.

### 1. Introduction

In order to conduct efficiently initial response activities such as fire-fighting and life-saving search-and-rescue operations just after a large earthquake such as the 1995 Kobe earthquake, it is important to make pertinent decisions based on actual disaster information and available resources. As a method and organization for collecting damage information efficiently, we proposed a time-spatial framework based on an investigation into the process of gathering earthquake damage information in municipalities that suffered during the Kobe earthquake $ ^{1} $ . In order to verify the validity of the method and organization, we first developed a prototype system that can support initial response activities after a large earthquake, considering ease of introducing it to fire services.

### 2. Concept of Building a System

In the case of severe damage such as that caused by the Kobe earthquake, it is very difficult to ensure adequate personnel even for fire services, because firefighters and their families may have been affected and usual traffic access may not be available. This situation will lead to an 'information gap' in which there is
insufficient information to decide how to take rational countermeasures.

Here, we consider a fire service headquarters as a base for information in and around a stricken site. A decision-maker must judge whether or not to set up a disaster countermeasure headquarters and to seek wide-area assistance.

Fire brigades will naturally be eager to start fire-fighting activities. Under ordinary circumstances, a quick response to a fire is essential, but it is not always good to fight fires immediately after a large earthquake, because not all the fires can be identified. For example, in the 1978 Miyagiken-Oki earthquake, most fire brigades attacked fires that they had identified just after the earthquake. However, more fires then broke out over a wide area, and they were late in fighting them $ ^{2)} $ . This experience shows that it is necessary to optimize the operation of fire brigades considering the total number of fires, but it is very difficult to do this properly based on the decision-maker's experience and sense. Thus, a system is needed that can support the decision-maker, based on actual disaster information and the prediction of occurrence and spreading of fires. The 1978 Miyagiken-Oki earthquake highlighted the following information problems:

(1) How quickly do we search and collect disaster information?

(2) How reliably do we transmit disaster information to the headquarters?

(3) How pertinently do we analyze and utilize the information for fire-fighting and rescue activities?

We try to overcome these problems through constructing the information system shown in Fig.1, which outlines the system concept and information flow. The system was designed based on the following considerations.

According to the result of a questionnaire survey of municipalities affected by the Kobe earthquake, staffs

Fig.1 Concept of support system for response activities
Fig.2 Means of collecting earthquake damage information in the 1995 Kobe Earthquake

Fig.3 Earthquake damage assessment system using PC

residents collected most of the damage information as shown in Fig.2, and informed the headquarters of fire departments or municipalities orally or by memos. However, this method is inadequate for visualizing the distribution of damage on a map instantaneously and for processing information because the data is in analogue form. Therefore, it is necessary to obtain digital data on damage rapidly. In addition, communication between headquarters and disaster areas must be secured in order to acquire damage information quickly. Since congestion of telecommunication routes always occurs after a large earthquake, it is necessary to develop a new communication network system between the stricken sites and headquarters without using public circuits.

At the headquarters, disaster information should be integrated and visualized using GIS, and supporting information for the firefighting strategy and tactics should be created and disseminated to the stricken area, based on real-time estimation of the earthquake damage, simulation of the spread of fire, and so on.

Although there are a few systems based on the similar concept at the fire departments in large cities such as Tokyo, Kyoto and so on, these are off-line systems.

### 3. Components of System

The components of the system, sub-system, and element technology needed with the lapse of time after an earthquake are described below.

### 3.1 Earthquake Damage Estimation System $ ^{3)} $

We have developed a simplified estimation system that provides an image of the damage just after an earthquake. Figure 3 shows the result for the Kobe earthquake. This system has the following features.

(1) It is possible to estimate the number of deaths, injured, refugees, fires, and collapsed wooden houses,

(2) It can be used for the whole country,

(3) Existing data are used, namely Digital National Land Information and National Census Data,

(4) The equipment is based on Windows machines,

(5) The system is easy to operate,

(6) It takes only several seconds to estimate the damage in a prefecture, and so on.

The system has already been deployed in more than 1,700 municipalities, fire services, institutes and so on
as of November 2001. However, the existing databases used in the simplified estimation system have a spatial resolution of 1-km square, and so are useful for grasping the damage over a wide area, but not small areas such as cities. We have therefore developed a system that can estimate damage with high spatial resolution for Yokosuka City to the south of Tokyo. In constructing the system, we took the ease of introduction to other municipalities into consideration: databases associated with soil conditions, houses and population have been constructed so that they can be easily derived as follows:

(1) Soil conditions: The land condition map is utilized as shown in Fig.4. Soil amplification factors are determined from the averaged S-wave velocity down to 30 m based on bore-hole data such as geology and N-values $ ^{4} $ . Digitalization was carried out by scanning the original land condition map for each soil classification.

(2) Houses: Commercially-available Digital Urban Maps (Zenrin Co., Zmap-II) contain information on the number of floors of each house. We regarded buildings with a first and /or second floor as wooden houses, and confirmed the accuracy compared with the actual number of wooden houses.

(3) Household: We used the population numbers for small blocks provided by Yokosuka City. The number of

people in a house was estimated by dividing the total population in each block by the number of houses in it.

The detailed damage estimation system was developed using GIS. The methods for evaluating the degree of earthquake damage were identical with those adopted in the simplified system. Figure 5 compares the seismic intensity distribution for the three different systems for the hypothetical Tokai earthquake. The results show that this system has a higher spatial resolution than the other methods.

在物理学中，能量守恒定律是一个基本原理，它表明在一个封闭系统中，能量既不能被创造也不能被销毁，只能从一种形式转换为另一种形式。例如，在化学反应中，反应物和产物的数量之和等于总物质的量。这一原理在物理学中是一个基本原理，它表明在一个封闭系统中，能量既不能被创造也不能被销毁，只能从一种形式转换为另一种形式。

Fig.4 Land condition map of Yokosuka City The mesh size of the right map is $ 250 \times 250m^{2} $ .

Fig.5 Comparison of estimated seismic intensity distribution for the Tokai earthquake Left: by the simplified earthquake damage estimation system using National Land Numerical Information Middle: by Yokosuka City Right: by the present study
### 3.2 Information Collection Terminal

In big cities such as Tokyo and Yokohama, cameras in high positions and helicopters will be used to assess the damage just after an earthquake. However, it is difficult to use these in a small town for mainly economic reasons. In addition, the obtained information is not sufficiently detailed such that an emergency response can be properly and smoothly conducted, so staffs in a municipality will organize information collection teams. Therefore, damage information including location should be digitalized so that it can be easily processed and displayed on the map. Visualization of the damage situation will lead to quick, accurate responses and smooth restoration as well as reconstruction countermeasures.

At the beginning, we developed the tool running Windows PC with a function that staffs in a municipality, firefighters, and community leaders can easily input damage information such as place, time, damage item, extent and so on at disaster sites by a stylus pen $ ^{1} $ . Since the PC costs about 450,000 yens and weighs roughly 1.4 kg, it seemed to be unsatisfactory on both ease of introducing it to municipalities and portability. Then, we have developed the advanced tool shown in Fig.6, which has the following features.

(1) Palm-size PC is used for portability, because its weight is about 250 g.

(2) It costs about 7-80,000 yens.

(2) Detailed map within a city, in which each house can be discriminated, is displayed.

(3) Position information can be acquired by clicking on the map.

(4) Damage data and extent can be input easily, and displayed on the map.

(5) A communication function enables data to be transmitted to a host computer.

(6) It can receive integrated damage information and simulation results such as fire spreading from a host computer.

The handy-type terminal runs Windows CE, and application development tools have been well marketed, so we could develop a palm-size PC based gathering tool.

For staffs responsible for collecting information in a part of the city, function (6) is particularly important, because they can assess their own situation throughout the city, and can also evacuate inhabitants to a safe place when the result of the fire-spreading simulation shows the danger situation. Firefighters can also take relevant fire-fighting strategy and tactics.

The persons in charge of gathering information review the damage situation and input data into the terminal as they walk around the disaster area. To support these operations, the terminal has three maps of different scale, so users can roughly grasp their positions on the large- and medium-scale maps. For ease of input, every operation can be done by merely clicking or dragging.

Fig.6 Handy-type damage gathering terminal Upper: Palm-size terminal

Lower: Display of total map, detailed map with icons showing damage, and input window
In the field experiment in Yokosuka City, it took about 90 minutes to search on foot and to input the various information on the 18 cases of damage associated with houses, life lines, fires and so on, in the area of about $ 300 \times 400 \, m^{2} $ for the hypothetical Tokai earthquake as shown in Fig.7.

Besides the handy-type tool, we have developed a terminal for cars. This can quickly and roughly search and collect damage information over a wide area, and also help nationwide large-area fire brigades to arrive at the stricken site rapidly, to assess the state of the site, and thus prepare for smooth activities before arrival, because it has a GPS navigation system, car speed sensor, road-matching technology, as well as detailed maps with support information such as water supply facilities, hazardous material facilities, refuges, gas stations and so on.

### 3.3 Communication Network System $ ^{5, 6)} $

As mentioned above, it is important to ensure the communication between disaster sites and the fire defense headquarters or the disaster prevention headquarters without congestion. Our institute has developed the FiReCos (Fire and Rescue Communication System) that enables firefighters to communicate smoothly among them at a disaster site. FiReCos is a high-performance, portable radio equipment based on PHS (personal handy phone system).

Fig.7 Searching area, route and superficial damage locations for the field experiment associated with the usability of the collection terminal in Yokosuka City
Since both digital wireless communication technology and multi-channel access systems are adopted, FiReCos is free from both radio interference and congestion, and is thus ideal as the basis for the communication network in the system. Furthermore, because the standard TCP/IP (Transmission Control Protocol/Internet Protocol) used in computer networks is adopted, the system can be easily connected to terminals and host computers that support TCP/IP for communication. FiReCos uses an extension mode, because it is not necessary to offer the usage of public radio waves. The transmission capacity is 32 kbps, the number of channels is 140, and frequency used is automatically selected by the multi-channel access method, so smooth transmission without congestion is ensured.

The network is constructed by connecting many cell stations as shown in Fig.8 each with an IP address using Ethernet LAN, which enables long-distance communication. With the aim of making practicable, Tamura et al. (2002) constructed a network combined several wireless LAN units and carried out field communication tests in Yokosuka City, and confirmed that the data communication can do via three wireless LAN units in about 1.5 km span between a field and the fire department $ ^{6} $ .

### 3.4 Real-Time Simulation System of Fire-Spreading

There are many wooden houses within small areas in Japan. Once a fire occurs, it tends to spread as seen in the 1923 Kanto earthquake, in which about 100,000 people were killed by fires. As many fires break out simultaneously in a large earthquake, fire brigades are often under-equipped to deal with them. Nevertheless, fire activities must be conducted to minimize the total burnt areas by appropriately arranging fire brigades. To devise the optimum fire-fighting strategy, it is indispensable to predict how the fires will spread as soon as possible based on actual information on the locations of fires and weather such as wind speed and direction.

In developing the real-time fire-spreading prediction system, we considered applicability to other areas, cost and labor. We obtained building data from commercially-available Digital Urban Maps (Zenrin Co., Zmap-II) as in developing the detailed earthquake damage estimation system.

Since the result must be produced quickly for supporting fire activities, we increased the processing speed by making the following assumptions:

(1) Fire spreads from house to house without flying sparks,

(2) Fire spreads from the wall to the center of a house,

and spreads to another house which burns most rapidly,

(3) Wind speed and direction are constant during burning,

(4) The fire-spreading paths are calculated in advance.

Figure 9 shows the result of the fire-spreading simulation for varying calculation conditions. The calculation time for three fires is about one minute.

### 3.5 Other Functions of Host Computer

The host computer at a fire department has the following functions:

## (1) Creating base map

It can generate the image data of three different-

Fig.8 Integrated radio communication system (FiReCos)