# Smart Disaster Response in Vehicular Tunnels: Technologies for Search and Rescue Applications
## 5 Discussion
Therefore, robots capable of acting as avatars for fire fighters are attracting increasing research interest. In particular, in a long space such as a tunnel, fast approach is important, and a high-speed flying robot can be a good solution. However, in the simulated fire experiment using this system, we found that the utilization of a robot is highly dependent on the ability to control the platform. In otherwords, since there is no fully autonomous platform so far, pilot intervention within a certain section is essential. Although a few autonomous algorithms make it possible to partially control obstacle avoidance, elaborate approach and rotation depend on the pilot's personal capability and experience. Moreover, if a robot depends on camera images in a dark tunnel, it has a high probability to collide with the surrounding vehicles or walls. Of course, it is possible to improve the durability of robots for this purpose by developing a platform that is robust against collision; however, collision with a running vehicle or collision with a victim can cause more serious damage. Therefore, a trained professional pilot is needed when the manual operation of a robot is performed, and it is necessary to confirm the entire path for the robot's navigation and the existence of the obstacles around the robot. To overcome these risk situations, various safety techniques, including attitude control, have been studied. Another problem is the limited battery capacity of the robot. Currently, most robots only have about 20 min of operation time, and charging time is relatively long. Therefore, if a robot is to be used over a long period of time, the battery operating time must be considered in advance. In a tunnel, the battery power consumption may increase due to wind and smoke resistance, so it is also necessary to confirm the environmental characteristics in advance. * Interaction with firefighters' operations. The authors of [48; 49] emphasized that fire fighters must arrive at the site of a fire within 10 min and perform rescue and fire suppression in order to successfully finish the fire fighting activities, because a vehicle fire usually reaches its peak within 5 to 10 min. If it is difficult to check the inside of a tunnel after arrival, it is recommended to use various monitoring devices and reconnaissance equipment. Although the CCTV, IoT sensors, radar devices, and robots proposed in this study are effective for initial information collection, additional fire activity information can be collected and provided during the fire suppression process. For example, when a large number of vehicles are involved in an accident with multiple collisions, and the flames spread to nearby vehicles due to explosions and wind, it is important to collect additional information, such as the direction of fire diffusion, additional explosion risk, and the locations of victims, during the fire suppression procedure. Therefore, if smoke is spreading due to additional fire, or there are difficulties to access the field due to dangerous materials, it is necessary to periodically share and confirm the collected information in the control center via the Internet or wireless networks. In addition, robot can be another solution for scouting or delivering relief items to spaces where it is difficult for fire fighters to approach due to the congestion of vehicles. However, if a fire has already reached its peak and the equipment is difficult to access, the fire brigade should use defensive tactics to prevent the fire spreading and then perform aggressive search and rescue activities after the fire has been suppressed to some extent. In other words, the proposed system should be appropriately combined with search and rescue activities before and after fire suppression rather than just direct fire suppression. Table 5 summarizes the overall operation scenario of how the proposed system can collaborate with the conventional responses of the fire brigade and tunnel supervisors. The proposed system is categorized into three responses.