# Emergency Repair Scheduling Model for Road Network Integrating Rescheduling Feature
## 3 Methodology
### Model Description and Assumptions  
In this study, complying with the rules of the RCPSP framework, the following assumptions are made to appropriately simplify the complexity of the emergency repair scheduling problem, in order to smoothly carry out overall model development and reasonably preserve the problem characteristics:  
1. The emergency repair scheduling problem in this study defines damaged road sections as repair activities, and the traveling routes of equipment resources between resource and disaster points as transit activities; thus, the equipment resources required for each repair activity are dispatched through transit activities.
2. Since the damage caused by a major natural disaster can be widely distributed, this study assumes that the decision maker of a maintenance unit, when planning emergency repair works for road sections, will appropriately delineate the scope of repair works within the unit's area of responsibility based on the location of its equipment resources and the location of each damaged road section.
3. The disaster information usually includes the geographical location of the disaster point, the volume of disaster treatment, the type of equipment resources required for recovery, and the maximum resource capacity of the disaster point at the same time due to space limitations. The repair activity defined in this study is excavation work for rockfall and debris slides at the disaster point. It assumes that all the necessary parameters for emergency repair scheduling have been collected through proper sources.
4. After a disaster, the main routes of a road network are prioritized by disaster-related vehicles, so this study assumes that the travel time of equipment resources traveling to the damaged road sections is known and the shortest, and is not affected by traffic flow or other factors. It is assumed that equipment resources, such as excavators and bulldozers, are transported to the disaster points by trailers. The major equipment resources considered here are excavators and bulldozers, which are the controlling resources of construction productivity for the problem domain of road network repair;  
Figure 1: Conceptual diagram of emergency repair scheduling model.  
other resources, such as workers and dump trucks, are assumed to be able to be provided upon request.
5. In this study, it is assumed that the disaster points are completely blocked and impassable until the repair work is completed, but in order to meet the actual demand for disaster relief, the repair work of each disaster point is assumed to be performed in such a way that vehicles can pass. The movement of equipment resources occurs only in the following two situations: (1) from the location where the resources are located to the disaster location; and (2) after the completion of repair activity at one disaster location, to another disaster location to perform repairs.
6. Once a repair activity for a disaster point begins, the resources cannot leave the disaster point or go to another disaster point for support, and repair activities cannot accept other resources to join the in-process repair work. Due to the emergency nature of the repair activity, it is assumed that all repair activities and transit activities are not allowed to be interrupted.