quake may have a more meaningful measure of severity than the earthquake's magnitude because intensity refers to the effects experienced at that place. The Haitian earthquake was assigned an MMI value of 9, indicating severe damage to poorly built structures (fallen chimneys, smokestacks, columns, monuments, and walls; heavy furniture overturned), as well as considerable damage in specially and well-designed frame structures, which were thrown out of plumb. Substantial buildings also incurred severe damage with partial collapses and buildings shifted off their foundations (2).Almost 1 month later, a magnitude 8.8 earthquake rocked the Chilean coast; however, it was assigned an MMI value of 8. Despite the significantly stronger event in Chile, the MMI value was lower because damage was less significant. Whereas Haiti took months to recover, Chile recovered within weeks. The key difference between these two examples is resilience.Resiliency, if properly understood and applied, can preclude many of the devastating effects of disasters. Resilient transportation systems may reduce the probability of failure within the system and reduce the consequences of any failure that occurs, thus improving recovery time. Understanding the resiliency of a transportation system after a disaster has occurred does little to mitigate the effects of the event. Thus, this paper expands on the conceptual framework developed by Heaslip et al. to assess the network resiliency of a system before a destabilizing event (3). This process identifies weaknesses within the network and provides decision makers with a flexible and robust method for quantifying resiliency. The information can be used to properly prioritize transportation investments to enhance network resiliency.
DEFINING RESILIENCEThe concept of resilience is broadly applied in many fields of study (e.g., engineering, psychology, sociology, economics). Similar concepts are flexibility, redundancy, reliability, elasticity, and risk management. In economics, the term "resilience" refers to the ability to recover quickly from a shock (shock counteraction), to withstand the effect of a shock (shock absorption), and to avoid the shock (vulnerability) (4). In social science, resilience is the capacity of a system that has been exposed to hazards to adapt by resisting or changing, so that it can reach and maintain an acceptable level of functioning and structure (5). In earthquake engineering, researchers define seismic resilience as the ability of social units (e.g., organizations, communities) to mitigate hazards, contain the effects of disasters, and carry out recovery activities in ways that minimize social disruption and reduce the effects of future earthquakes (6). Community seismic resilience is the capacity to absorb stress, manage it, and recover from it (7). More generally, resilience is the capacity to absorb shocks gracefully (8).The concept of resilience has been studied in the field of transportation engineering as well. Conceptual frameworks have been created
Evaluation of...