Abstract
When a natural disaster hits an urban area, the first 72 h after are the most critical. After that period the probability of finding survivors falls dramatically, therefore the search and rescue activities in that area must be conducted as quickly and effectively as possible. These activities are often improvised by first responders, stemming from the lack of communication and information support needed for making decisions in the field. Unfortunately, improvisations reduce the effectiveness and efficiency of the activities, in turn, affecting the number of people that can be rescued. To address this challenge, this article introduces the concept of a human-centric wireless sensor network, as an infrastructure that supports the capture and delivery of shared information in the field. These networks help increase the information availability, and therefore, the efficiency and effectiveness of the emergency response process. The use of these networks, which is complimentary to the currently used VHF/UHF radio systems, was evaluated using a simulated scenario and also through the feedback provided by an expert in urban search and rescue. The obtained results are highly encouraging.
1. Introduction
Every year natural disasters, such as earthquakes, hurricanes, volcanic eruptions and tsunamis, hit urban areas. During the first 72 h after the event, usually known as the ‘‘golden relief time’’, the response process is focused on searching and rescuing people [1]. The probability to find survivors after that time is increasingly low [2]. Coburn et al. [3] report the evolution of the survival rate over time, by analyzing the results of four earthquakes (Fig. 1). The analysis indicates the survival rate does not evolve in the same way in every extreme event; however, it is clear that the first 72 h after the occurrence are the most critical ones to search and rescue efforts. Similarly, after studying the survival rate in earthquakes, Fiedrich et al. [4] proposed a model to estimate such a rate (Fig. 2). The prediction model also indicates that the first 72 h are the most critical for rescuing survivors. Therefore the SAR activities must be quick and effective, because the number of survivors is directly related to such efficiency.
7. Conclusions and future work
The typical limitations to count on useful and on time information in the field represent still open problems. Most proposals trying to deal with this issue address a part of this problem or require specialized and expensive equipment. For that reason, the most wellknown and used method of sharing information in the field involves physical marks that first responders make on the infrastructure.
To address this challenge this article introduces the concept of human-based wireless sensor network, which can be seen as opportunistic networks that intend to provide real-time communication support among the nodes. Such nodes are mainly humanbased sensors, but the network also considers the inclusion of regular sensors, mules and witness units. This network is multi-sensor and collaborative, and the HBS are the nodes mainly responsible for information dissemination and fusion.
