# Smart Disaster Response in Vehicular Tunnels: Technologies for Search and Rescue Applications
## 3 Proposed Disaster Response Systems for Tunnel Accidents
### Localization and Commanding for Firefighters  
By using the IoT sensor and robot described above, the firefighter collects information on the situation inside the tunnel. If it is judged that it is safe, even if the rescue crew is present, the actual fire brigade starts to enter. At this time, the most important duty of the fire brigade is to find and rescue the survivors in the vehicles involved in the accident. That is, it is important to identify the accurate location of survivors and fire fighters to support efficient search and rescue operations. For this purpose, the survivors can announce their location through their voices, but if they use smart phone and radio frequency identification (RFID) technology, they can transmit their location information through the wireless network. Fire fighters can also transmit their locations to the control center using RFID readers and dedicated terminals. In this proposed system, RFID tags are installed in the tunnel at regular intervals, and a user of an RFID reader approaches the tags and measures their coordinates and time. Then, the location information is transmitted to the remote control center. Although RFID systems vary according to RF specifications, they are generally recognizable at distances of 5 to 30 m, and tags are very cheap, so they can be installed over a wide area of the tunnel. A conceptual diagram of the constructed system is shown in Figure 10. If an RFID reader reads a tag installed in the tunnel in advance, the data can be identified through a smart device paired with Bluetooth, and the corresponding coordinates are displayed on the map. Meanwhile, the process in which a fire fighter searches for victims is repeated at least three times in the same area. This is because it is necessary to reaffirm that there are no victims who are found in the field. To do this, we divide the search area for each accident vehicle and report the number of  
Figure 10: Localization and Repeated Search. times a search of the area is completed to the control center. Thereafter, the control center notifies the firefighter of the sections that have not been repeatedly searched more than three times, so that no unconfirmed sections are generated. At this time, the completion of the search in the corresponding area needs to be explicitly input through the application of the mobile terminal held by the firefighter. In other words, it is up to a firefighter's personal judgment to decide whether or not to complete search operation in a certain area. In Figure 10, three cars are divided into three search areas when the vehicles cause a chain collision accident. The positions of the three vehicles can be confirmed by using the previously proposed radar system, and the control server dynamically divides the accident spot into three search areas based on the location of stopped vehicles with the default option. Of course, according to the fire commander's field judgment, the search area can be manually adjusted. If more precise localization than that achieved by RFID is needed, the system can adopt an UWB technology. The proposed system is also compatible with UWB RF. It has been confirmed that it provides precise positioning with accuracy within 20 cm indoors when Decawave DW1000 (commercial product) [40] is used. As shown in Figure 11, the construction model for the basic positioning can measure the x, y coordinates through trilateration by receiving the distance information using UWB signals from three anchor nodes. Pairing connection using Bluetooth is also possible for interworking with existing smart devices. The measured data is displayed in real time on the map program in the terminal or the server computer. In Figure 10, two fire fighters are sent into search area 2 and search area 3 indicated by blue dots. In addition, a red dot indicates a victim and helps the adjacent fire fighter to rescue the victim.