of US$151 billion a year.<sup>12</sup> And long-term impact may be significantly higher than short-term losses as firms experience the knock-on effects of foregone productivity.<sup>13</sup> Conversely, there is evidence of significant returns associated with improved maintenance and resilience to climate change and natural disasters. Significant returns are associated with improved maintenance that precludes excessive repair costs associated with rebuilding significantly damaged infrastructure.<sup>14</sup> Moreover, economic benefits are expected for developing countries that invest in resilient infrastructure. Hallegatte, Rentschler, and Rozenberg estimate net benefits of US$4 for every US$1 invested in resilient infrastructure due to savings in repair costs as well as avoided social and economic damages.<sup>15</sup>

# The Resilience Concept

The potential benefits of building more resilient infrastructure, particularly in disaster-vulnerable contexts, along with an acceptance of deep uncertainty associated with climate change, compels a resilience approach to infrastructure development. While disaster risk management (DRM) is a core component of infrastructure resilience, the concept for resilience additionally deals with process and resource features that can extend the capacity of a system to withstand and recover from shocks and stressors.

The Intergovernmental Panel on Climate Change defines resilience as "the ability of a system and its component parts to anticipate, absorb, accommodate or recover from the effects of a hazardous event in a timely and efficient manner, including through ensuring the preservation, restoration or improvement of its essential basic structures and functions" (2012).<sup>16</sup> Moreover, infrastructure resilience has multiple levels with different types of benefits. The resilience of individual assets allows components of a system to withstand shocks, thus reducing overall costs. The resilience of networked infrastructure services refers to higher reliability at the system level. And the resilience of users captures the extent of negative impacts on people and economies as the result of a hazard.<sup>17</sup> Resilient infrastructure assets are robust and designed to anticipate failures; resourceful to maintain or restore functionality following a shock; and built to be flexible, recoverable, and adaptable to change.<sup>18</sup> Robustness is gained via design and maintenance inputs to an asset that make it particularly durable or by building system redundancies. The robustness of an asset may be increased by engineering means, for example, by strengthening a structure identified as having high risk of exposure to a certain hazard. In the context of road transport infrastructure, this may be done via adaptation measures such as soil improvement, the addition of retaining walls, installation of more robust foundations and reinforcements, and improved drainage.<sup>19</sup>

> 12 Rentschler, J., Kornejew, M., Hallegatte, S., Braese, J., & Obolensky, M. (draft, 2019). Underutilized potential: The business costs of unreliable infrastructure in developing countries. Global Facility for Disaster Reduction and Recovery, World Bank, Washington DC, and Bonn Graduate School of Economics, University of Bonn, Germany.

> 13 Braese, J., Rentschler, J., & Hallegatte, S. (forthcoming, 2019). Resilient infrastructure for thriving firms: A review of the evidence. Global Facility for Disaster Reduction and Recovery. World Bank, Washington DC.

> 14 Rioja, F. (2013). What is the value of Infrastructure Maintenance? A Survey. Infrastructure and Land Policies, 13, 347-365.

> 15 Hallegatte, S., Rentschler, J., & Rozenberg, J. (2019). Lifelines: The Resilient Infrastructure Opportunity. Washington, DC: World Bank. https://openknowledge.worldbank.org/handle/10986/31805

> 16 IPCC (2014). Climate Change 2014: Impacts, Adaptation, and Vulnerability. Working Group II contribution to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. <u>http://www.ipcc.ch/report/ar5/wg2/</u>

> 17 Hallegatte, S., Rentschler, J., & Rozenberg, J. (2019). Lifelines: The Resilient Infrastructure Opportunity. Washington, DC: World Bank. https://openknowledge.worldbank.org/handle/10986/31805

> 18 SuRe (2016). The Standard for Sustainable and Resilient Infrastructure v 0.3. Global Infrastructure Basel. 27 July 2016. - - <u>http://www.gib foundation.org/sure standard/</u>

> 19 Miyamoto & World Bank (2019). Overview of engineering options for increasing infrastructure resilience: Final report. February 2019.

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