# Emergency Repair Scheduling Model for Road Network Integrating Rescheduling Feature
## 1 Introduction  
The strike of a devastating hazard event causes significant damage to the road network and creates a chaotic situation [1, 2, 3, 4]. Thus, effective disaster management in this chaotic post disaster situation becomes an inevitable demand to overcome post disaster problems and ensure road network functionality [5, 6]. In disaster management, there are four relevant phases which include mitigation, preparedness, response, and recovery [6, 7]. The response phase is the execution of an emergency procedure and utilizes all necessary resources to recover all disaster-affected communities back to normal life [5]. Moreover, the response phase is not only conducted by air, but also absolutely relies on road networks (highways, tunnels, and bridges) to support survivor evacuation, rescue operations, and societal recovery [8, 9, 10]. Maintenance units always prepare for the challenge of how to effectively allocate emergency repair resources (work crews or equipment) to recover damaged facilities in their areas of responsibility so that rescue and supplies can be brought into disaster areasmore quickly. Significant damage to road networks always makes rescue and supplies distribution difficult for the affected locations [11] and delays the evacuation of survivors to shelter [12]. Such unavoidable conditions did happen in the post disaster event of the Chi-Chi earthquake that occurred in Taiwan, on 21 September 1999, where the affected population which lived in villages were isolated because of the damaged roads and no bypasses in mountain terrain [13]. The same post disaster situation also occurred in the Wenchuan earthquake in Sichuan Province, China, on 12 May 2008, which destructed a road network of 53 km and made many impacted villages isolated [14]. Learning from past experiences, people in the affected disaster area need to be rescued immediately. A delay in distribution logistics and medical aid can lead to an increasing number of death casualties [15]. Thus, a quick post disaster response to perform an emergency repair of damaged road networks in a short time is crucially significant [11; 16]. There are some key challenges to performing emergency repair scheduling in the chaotic situation of the aftermath of a disaster, compared to routine maintenance scheduling. From previous research, those challenges are elaborated as follows [17; 18; 19; 20; 21; 22]: (1) an unpredictable situation because of inaccurate information, (2) difficulties to perform ideal communication and coordination among the involved humanitarian relief parties, (3) the available resources are often overwhelmed compared to the scale of the chaotic situation (e.g., food supply, manpower, vehicle capacity, heavy equipment, fuel, and medicines), (4) high probability of second-wave threats, and (5) the sequence of repair activities. Therefore, the repair schedule must satisfy the following two characteristics: First, although the number and location of available repair equipment resources within the maintenance unit's area of responsibility are known, under the condition of limited resources, the productivity of repair equipment resources must be coordinated by the decision maker before allocation, so that the schedule can adapt to real disaster conditions and improve the efficiency of the repair project with the best resource allocation [22; 23]; second, due to the topography or geographic location, not all damaged facilities are directly connected to the location of repair resources, which will be called a \"resource point\" later, so the sequence of repair activities at disaster points must take into account the limitations of the actual area and complete the overall repair project as soon as possible [24; 25]. Inspired by those challenges and the necessity of emergency repair scheduling for road networks, this study proposes an optimization model for emergency repair scheduling problems, based on a framework of the Resource-Constrained Project Scheduling Problem (RCPSP).