Approved by the Committee on Technical Advancement on January 8, 2021
Approved by the Public Policy Committee on February 3, 2021
Adopted by the Board of Direction on April 30, 2021


The American Society of Civil Engineers (ASCE) supports a unified set of definitions for the concepts of critical infrastructure, hazards, multihazards, and resilience as follows:

  • Critical infrastructure includes systems, facilities, and assets so vital that their destruction or incapacitation would have a debilitating impact on national security, the economy or public health, safety, and welfare. Critical infrastructure may cross political boundaries and may be built (such as structural, energy, water, transportation, and communication systems), natural (such as surface or ground water resources), or virtual (such as cyber, electronic data, and information systems).
  • Hazards include events and conditions such as natural occurrences across varying temporal and spatial scales, accidents, and deliberate acts that damage, reduce functionality and services, and affect social and economic outcomes that lead to illness, injury, or loss of life.
  • Multihazards denotes the occurrence of more than one hazard and the interaction among them as independent, simultaneous, coupled, successive, cascading, or compounding, that threaten a specific community or geographic region.
  • Resilience is the ability to plan, prepare for, mitigate, and adapt to changing conditions from hazards to enable rapid recovery of physical, social, economic, and ecological infrastructure. Improving resilience before or following a hazard event should engage physical infrastructure and social systems with adaptive capacity to ensure rapid return to functionality, accounting for interdependencies within and across all sectors.


In the post 9/11 environment, there have been various definitions of critical infrastructure, all-hazards, multihazards, and resilience. Without unified definitions, it is difficult to develop industry and building standards and useful metrics for progress in this vital area.


As an individual member professional organization representing practitioners in the public and private sectors, as well as educators, ASCE is uniquely qualified to provide definitions which can be used to clarify the discussion in government and the infrastructure industry at large. An all-hazards approach is used in the government and emergency management communities, while the engineering community uses a multihazards approach to address infrastructure resilience. It is important to recognize and define the context for both approaches. These baseline definitions will aid in the development of standards and federal, regional, state, and local legislation and regulation.

ASCE Policy Statement 518
First Approved in 2006