# Smart Disaster Response in Vehicular Tunnels: Technologies for Search and Rescue Applications
## 3 Proposed Disaster Response Systems for Tunnel Accidents
### IoT and Vision Sensor for Early Fire Detection  
Most tunnel fires occur in vehicles that are running, so the fire is first detected by the driver. The driver makes an emergency stop and alerts the status to the control center via an emergency call, but if the driver is injured or unaware of the fire, the fire sensors installed in the tunnel must detect it. Currently, one of most accurate and robust types of fire detection equipment is fiber optic cable, which measures the distribution temperature of objects and senses temperature changes by distance and region. The advantage of the fiber-optic method is that it has a low maintenance cost. In addition, it provides accurate measurements and is almost permanently usable. However, the initial installation cost is high and the scalability is low. Figure 2 shows the overall architecture of the fiber optic cable system. The second fire recognition system is a camera-based monitoring technique such as CCTV, which is relatively inexpensive to install and most commonly used. In general, it is possible to detect objects in the range of 100 m to 150 m by using a high-definition (HD) camera, and it is possible to judge the situation, in that the field can be checked in real time. However, there is an inconvenience that the administrator must constantly perform visual monitoring. To this end, it is possible to recognize objects and the fire situations in real time using IoT-based image-processing technology. In the proposed system, the occurrence of a fire is judged based on the diffusion pattern of flame and smoke. Although the flame shape tends to be changed irregularly with different environmental conditions, it has the unique color value in the specific range. In order to distinguish the color of the flame in the range, we generate the digital image which is converted into hue-saturation-value (HSV) color space by using the hue values except for the brightness and saturation. Then, the scheme extracts the red, green,  
Figure 2: Fiber Optic Cable. blue (RGB), H, V values of the pixels in order to configure the candidate region which is considered as real flame. For this calculation, we define expression (1) as follows. \[\mathrm{F_{1}(x,y)}=\left\{ \begin{array}{c}1,\left\{\begin{array}{c}\mathrm{ RGB(x,y)>RGB_{mean}}\\ \mathrm{H(x,y)>H_{mean},H(x,y)<H_{mean}}\\ \mathrm{V(x,y)>V_{mean}}\\ 0,\mathrm{otherwise}\end{array}\right.\\ \end{array} \right. \tag{1}\]  
By adopting expression (1) into digital pixel, the proposed scheme generates a flame candidate binary image, called \(\mathrm{F_{1}}\). After consecutive checking the fire zone candidate, if the count variable is more than the threshold candidate zones (it is set to 100) and the variable is concentrated more than 3 areas, the candidate region is judged to be a real fire zone. The overall operations and recognition algorithm of proposed scheme are summarized in Figure 3.  
The proposed vision algorithm enables real-time detection without human intervention by ensuring the recognition time of 3 to 10 s after the first fire occurs. Figure 4 shows the technique of detecting smoke and flame through camera images. The third proposed device is a portable, scalable, wireless communication-based compact fire detector. Recently, the weight reduction of sensors has enabled the development of sensors that incorporate heat, smoke, flame, and ultraviolet (UV)/infrared (IR) sensors. Figure 5 shows an integrated sensor platform for producing fire alerts using WiFi. The proposed system can be installed at intervals of 50 to 100 m depending on the WiFi transmission range. In addition to heat and smoke detection, motion sensors can be used to monitor emergency situations in a variety of environments, such as detecting activity of a victim. The detailed message format for transmission is shown in Figure 6. Each data field has 1 byte and the total message size is 14 bytes.