INNOVATION January-February 2022

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by deterioration at the failure location over an extended period of time. It will be very important to analyze, as thoroughly as any post-failure investigation permits, the dike failures that occurred in the November 2021 flood. Equally instructive will be a comparison with dike failure statistics from historic flood events, so as to place the impacts of this storm in a broader context. TRANSPORTATION IMPACTS During the most critical days following the storms, the transportation system was uniquely stressed. First, heavily damaged infrastructure resulted in the need for rerouting and subsequently, significant delays for travelers and freight movement by road and rail. At the same time, acute demands arose due to orders for thousands of residents of impacted communities to evacuate,

while emergency response and supplies were mobilized. Thus, transportation network capacity was heavily reduced at the same time significant demands arose, all while the situation changed rapidly in this early period. Tactical multi-modalism, with the objective to supply additional, necessary, and targeted transportation capacity in a short timeframe via rail and air, was critical in transporting people and supplies. During emergency repairs, safety concerns arose as necessary reroutes were made to facilities not designed to accommodate these levels and types of traffic. Some communities continued (and continue, at the time of writing) to lack highway access while emergency repair work took place. In building transportation resilience against extreme weather events, we

Dike failures are broadly categorized with reference to processes of external erosion of the dike surface, internal erosion through the body of the dike and/ or its foundation, and slope instability associated with deformation along a slip surface within and/or below the embankment of the dike. Flooding, as a consequence of these processes, takes the form of flow over the crest of a dike (i.e., overtopping/overflowing), flow through an opening in the dike (i.e., breach), or a combination of both. Assessments of dike performance inform the management of a flood defense system, and technical analysis of dike failures is particularly instructive when a review is undertaken with the objective of learning lessons for purposes of asset management. Failure has generally been found a result of interrelated factors, and is often preceded

Aerial view (looking northeast) of breach location and repair on

the Sumas River Dike. P HoTo : J oNATHAN f ANNIN

look to long-term infrastructure design and maintenance strategies, as well as emergency transportation operations planning, amongst other activities. Critically, we must combine the work of, and inputs from, different engineering disciplines together in order to make better resource allocation decisions involving risk mitigation across the system. This work is challenging because natural disasters and their impacts are inherently uncertain over time, space, scale, and scope. Availability of detailed transportation data also continues to be a challenge. THE IMPORTANCE OF AN INFORMED UNDERSTANDING By any socio-economic measure, the cumulative impact of the November 2021 landslides and floods on civil infrastructure proved disastrous. The Insurance Bureau of Canada, in December 2021, declared it the most costly severe weather event in the province’s history, based on estimates of insured damage.

The additional uninsured losses and damage to infrastructure will ultimately be borne by government and taxpayers. In the transition to rebuilding with greater resilience, it is incumbent on all involved to develop an informed understanding of the many vulnerabilities exposed in the infrastructure systems that serve the people of British Columbia. This step is imperative, if we are to properly address the lessons to be learned for the future resilience of our critical infrastructure.

On December 15, 2021, the authors invited government representatives, industry professionals, and journalists, to an online technical briefing, where they shared preliminary observations on the November 2021 storm and its impacts. To view the briefing, visit youtube.com and enter “UBC Technical Briefing” in the search box.

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