Alternative or back-up means created within an infrastructure system to accommodate disruption, extreme pressures, or surges in demand. It includes diversity, i.e., the presence of multiple ways to achieve a given need or fulfil a particular function.
1. Redundancy increases reliability. See also “Reliability”.
Adapted from Asian Development Bank (2016). Enhancing Urban Climate Change Resilience: Seven Entry Points for Action.
Use of redundancy in full suppression of three Wildland Urban Interface (WUI) wildfires in south-western United States in the summer of 2010
Researchers analyzed the response strategies to three large-scale wildfires that resulted in the evacuation of residents and threatened key infrastructure assets. The researchers identified four redundancy strategies: backup, cross functionality, duplication, and cross check.
- The Backup strategy involved bringing in personnel and equipment from outside to the affected area to scale up and meet the changing needs. In anticipation of technological limitations and failures, backup plans were put in place to restore or prevent loss of functionality.
- Cross Functionality involved allocating human and technology resources to serve multiple roles or functions within the system. This allowed for effective resource management and the ability to do more with less.
- Duplication involved the use of multiple communication technologies, such as face-to-face, radio, and cell phones, which were essential for effective incident management. This also involved multiple individuals holding key positions on the incident command team, allowing for cooperating agencies to easily locate the person they needed.
- Cross Check strategies were implemented to detect and correct errors, including procedural, information, and tactical verification. Fire operation planners worked with archaeological or biological resource advisors to protect cultural sites and sensitive habitats from damage. Safety officers were employed at various levels to ensure the safety of firefighters and community members.
It is crucial to note that each redundancy type has its own strengths and risks when it comes to enhancing system resilience.
Source: Nowell, B., Bodkin, C. P., & Bayoumi, D. (2017). Redundancy as a strategy in disaster response systems: A pathway to resilience or a recipe for disaster? Journal of Contingencies and Crisis Management, 25(3), 123–135. doi:10.1111/1468-5973.12178