Severe Weather: Planning for the Average
When natural disasters occur, it is understandable to ask, "why?" when they result in loss of life and property. We need answers. Heck, we may need to point the finger of blame at somebody, anybody, to help rationalize these events. Seeing the scale of the sheer destruction resulting not from process failures, machinery or equipment, or even human error, but mother nature challenges conventional wisdom regarding how we analyze incidents.
In this case, I refer to the recent destruction of building structures that sheltered people and the subsequent loss of life due to tornadoes across five states on December 10, 2021. While we should ask questions, the lens through which we view these events must change once we realize that we are dealing with an event well beyond human control.
We have all heard severe weather warnings, and we have all heard forecasts of the possibility of severe thunderstorms, and yes, technically, all thunderstorms can produce tornados. But suppose we stack this knowledge up with our culturally acceptable risk tolerance (regarding weather). In that case, we can see that no reasonable person could have known these events would occur, certainly not on this scale, nor would they have placed themselves or others in a hazardous situation. Does this mean we do not take severe weather emergencies seriously? Of course not. It does mean that a reasonable person would accept this common risk, being inside a sound structure with a known area to shelter if the need arises - beyond that, what can we do? Can we plan for the absolute worst-case scenario? Is that even realistic? We usually land somewhere on the spectrum of planning for the average event in our society. To be clear, I am not talking about workplace safety specifically, but what we generally find acceptable in society.
Let's take the 100-year flood as an example. The 100-year flood has a one percent chance of being equaled or exceeded during any given year. As the time indicates, the 100-year flood is not frequent but relatively rare. Therefore, most communities use a design frequency of 5 to 20 years for their stormwater systems. This level of protection takes care of most surface water problems over this period and provides a reasonable balance between safety and cost.
The vast majority of floods in the U.S. are not 100-year events, regardless of what every media story reports. Using the term "100-year flood" inaccurately to describe much lesser floods creates the misconception that 100-year floods occur every few years, which can cause the public to question our preparation for such events.
So what are we to do when these natural events occur? Do we not ask questions? Of course not, but we do need to ask them differently. As for the recent tornadoes, it is reasonable to presume the buildings in the affected areas of destruction were designed, built, and up to code. However, building designs have historically not accounted for tornadoes. According to the National Institute of Standards and Technology (NIST), the strength of tornadoes and a common perception that the risk of being struck by one is low have fed into a misconception that addressing tornadoes in building designs would be far too costly.
Can we use the same middle-ground for tornados as the 5 to 20-year flood approach? Let's look at an example. In 2011, when a record-breaking tornado season wreaked havoc across the U.S., NIST thoroughly investigated one of the worst events that year, a tornado rated as the most severe on the Enhanced Fujita (EF) Scale — an EF5 — that ripped through Joplin, Missouri. The more than 8,000 buildings damaged in the tornado's wake were schools, big-box stores, nursing homes, fire stations, and a major hospital.
The NIST team found that although the most powerful winds laid waste to buildings near the tornado center, more than 70% of the total damage path stemmed from lower wind speeds farther out. And designing for that level of wind is much more economically viable. But understand this, it will not eliminate all loss of life and property, which is the bargain we make as a society. Building codes and standards don't require design for the worst possible floods, hurricanes, and earthquakes either - we can take the same approach for tornadoes, and NIST has a draft building standards proposal to address this issue.
The draft of the new building standards features first-of-a-kind tornado hazard maps meant to guide the design of facilities, such as schools, fire stations, and hospitals, based on their size and geographic location. For the first time, tornado-prone regions will have guidance to better design new buildings to withstand these events. The hope is the standard will be adopted by the model building codes (maintained by independent codes and standards organizations) and incorporated into U.S. state and local building codes, saving more lives.
We must reach a collective agreement between individuals, business leaders, and local, state, and federal regulatory agencies regarding looking for fault, considering the overwhelming evidence that [anyone] could have done little to nothing to anticipate the disaster. Asking why we did not place our shelter-in-place (SIP) area five feet to the east will not be beneficial, especially since these naturally occurring events are different. Asking whether there was a working alert system may not be all that beneficial, considering the varying regulatory requirements from state to state, even county to county within states. I mentioned earlier about our lens - I am referring to a forward-looking lens, like a telescope, rather than a rearview mirror.
A rearview mirror will ask why we did not have something in place that was not previously required. Hindsight bias is not particularly helpful in this case. The forward-looking lens can ask the same questions but in a different context:
- Should buildings contain different design criteria for materials and construction?
- Should we require structural requirements for SIP areas inside a large open structure, such as a warehouse or manufacturing facility?
- Should we integrate the national weather service alert system into existing building notifications?
These are forward-looking improvements that should be discussed based on what we learn. Proposed building standards like the one NIST drafted aim to answer these appropriate questions.
In the meantime, take all reasonable and prudent actions to protect your loved ones, to improve your homes against severe weather events, and please find ways to assist those affected communities.
*I wrote this article for an upcoming podcast episode. Please share your thoughts below.
