# Coordination in Emergency Response System Design:
## 2 Literature Review  
In this section, we provide a selective overview of the coverage formulations, and the reader is referred to [5] for a comprehensive review. Table 1 depicts some of the early work on maximum covering models indicating their objective and coverage threshold representation. It is important to note that all these models focus on the use of a single specialty team for responding to an emergency. The cooperation needed among different types of emergency response resources is not captured by these models. Ref. [16] focused on random link failures and provide a 0-1 linear optimization model to locate response facilities. Their objective is to maximize the rescue coverage. Ref. [17] presented a multi-objective version of the maximal conditional covering location problem. Their model is applied to the relocation of hierarchical emergency response facilities. Extending their work on gradual coverage, ref. [18] focused on joint partial coverage by aggregating the coverage provided by multiple facilities. Based on fault tree analysis, ref. [19] analyzed the evolution of emergency incidents. Ref. [20] studied the storage location problem for emergency supply, where the goal is decreasing the cost of response supplies when large-scale emergency response is needed. Emergency evacuation has attracted the attention of some researchers including [21; 22; 23]. This stream of research is mainly based on simulation modeling and network design, and focuses on traffic flow, scheduling design, traffic signal, traffic routing, the information of timely traffic, and activity behavior. The objectives include designing rapid response strategies, quickly transferring evacuees, and mitigating disaster consequences. Table 2 provides a comparison of the papers, focusing on hazmat transportation, with regards to the type of transport network considered and the sub-problem involved in the developed model. These papers assume that the hazmat incident will be attended by specialized hazmat response teams. The first model was developed by [24], where the emergency facility is in a rural road network to respond to a spill incident. Since the incident probabilities in this context are very low [25], the rescue teams are assumed always to be available. Ref. [26] assumed a pre-set coverage distance in developing their mathematical model for the arc-covering problem defined on a highway network. Ref. [27] focused on the travel time, evacuation, risk and cost, and optimized location decisions and coverage of response deployment for the hazmat distribution routes. Recently, ref. [28] proposed a bi-level model to design the hazmat transportation network and locates the emergency team based on a road network between specified OD pairs. The average response time was considered to assess the corresponding risk. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Paper** & **Objective** & **Coverage Threshold** \\ \hline [PERSON] (1982, 1983) [6] & Max expected no. of covered nodes & Distance \\ [PERSON] and [PERSON] (1986) [7] & Max the back-up coverage & Distance \\ [PERSON] et al. (1997) [8] & Max the no. of nodes covered twice & Distance \\ [PERSON] and [PERSON] (1998) [9] & Max the no. of covered nodes & Waiting time in queue \\ [PERSON] et al. (2001) [10] & Max the no. of covered nodes & Response time \\ [PERSON] et al. (2003) [11] & Max the no. of covered nodes & Distance \\ [PERSON] et al. (2003) [12] & Max the no. of covered nodes & Gradual coverage \\ [PERSON] et al. (2005) [13] & Max expected no. of covered nodes & Distance \\ [PERSON] et al. (2007) [14] & Max the no. of covered nodes & Coverage level \\ [PERSON] and [PERSON] (2010) [15] & Local reliability & Distance \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Early covering models in the literature. During the past five years, there has been renewed interest in hazmat emergency response. Ref. [29] studied the location and capacity of hazardous waste storage sites and the development of emergency response policies.