Don’t Have a Wind Management Plan? Here’s Why Your Event Needs One.January 31, 2022
The idea of a wind management plan may be completely new to you. Although wind management planning is an accepted part of the event planning process in other parts of the world, the standards for event safety here in Canada have not yet caught up to those of our international counterparts.
So, what is a wind management plan? Before we dive into the details, it’s important to understand why wind management plans exist and how they can protect the safety of your attendees.
Why Do I Need a Wind Management Plan?
Events exist to create positive experiences for people; they are meant to delight, engage, or educate attendees. However, the often-temporary nature of in-person events, as well as their typical format (large gatherings of people), means that they carry inherent risks for those same attendees.
As an event planner, you are responsible for identifying those risks to ensure the safety of your guests. While wind management planning may not be common practice in North America, other examples of risk assessment and mitigation are routine for most Canadian event organizers. Fire safety, crowd management, and emergency procedures should all be familiar concepts.
However, we often overlook the fact that wind can pose a risk to attendees and employees of outdoor events. Temporary outdoor events depend on temporary structures like stages, tents and fencing – all of which are susceptible to wind. At best, a flyaway tent is an inconvenience. At worst, it can pose a serious threat of injury or even death.
You might think that the odds of a temporary structure blowing over are slim, but the truth is that this is a common occurrence. We have seen portable toilets blow over at an outdoor show in Calgary. We have witnessed the tragedy of stages collapsing due to high winds in the United States and Brazil. And here at Modu-Loc, we are all too familiar with the negative impact of wind on our temporary fence panels.
It can take just one strong gust of wind to topple a temporary structure. For instance, consider that a basic line of 6’ high temporary fence might fail at wind gusts above 62 kilometres per hour (km/h). While that may sound like a high number, wind gusts can reach well above 62 km/h in many parts of Canada. The table below lists some major Canadian cities and indicates the number of months each city experienced winds of at least 62 km/h in the past year.
Source: https://www.weatherstats.ca/. Data accessed January 28, 2022.
As you can see, high winds are not uncommon in many Canadian cities where outdoor events take place. These wind gusts can create dangerous situations for your attendees and workers, so it’s crucial to have a wind management plan in place.
What is a Wind Management Plan?
A wind management plan seeks to identify the possible risks associated with wind, and outlines the proactive and reactive actions to take at each level of risk.
The key elements of a wind management plan include:
- Roles and responsibilities
- A plan or process for monitoring wind speed
- Wind velocities and potential risks at each threshold
- Actions to be taken at each threshold based on the risks identified
Tips for Creating a Wind Management Plan
Knowing where to start when designing your wind management plan can be tough. Below, you’ll find some tips to help you get started.
Create a List of Your Temporary Demountable Structures
To identify possible wind-related risks for your event, start by looking at the temporary demountable structures you’ll have on site. This is a term commonly used in the United Kingdom to refer to any structure that is designed to be quickly constructed and then dismantled after a short period of use. In Canada, they may be called “demountable event structures” or sometimes simply “temporary structures”.
Whatever you decide to call them, most outdoor events rely on demountable event structures. They include things like stages, tents, temporary fencing, and grandstands or bleachers.
Demountable structures are governed by provincial building codes. However, unlike permanent buildings, temporary demountable structures are not built for longevity. Their temporary nature makes them more susceptible to high winds and inclement weather.
For your wind management plan, document every demountable event structure you’ll have on site and then work with the suppliers of those structures to understand their wind ratings. Your supplier should be able to provide you with engineering drawings and wind test results for the structure.
Now that you have a list of temporary structures and their wind ratings, you can start to identify possible risks.
Use a Wind Velocity Scale to Identify Possible Risks
It’s likely that your wind management plan will be used by multiple people on your team, so it’s important to establish a standard for measuring wind severity.
The Beaufort scale is commonly used for wind management planning as it offers visual cues for different wind speeds. Here is the Beaufort scale with descriptions and associated wind speeds displayed in kilometres per hour:
Note that while the Beaufort scale reaches a force of 12, your wind management plan should account for a complete shutdown of event operations before winds ever reach that speed.
Whatever scale you decide to use, identify and document the potential risks at each level or rating. This is where you would reference the wind rating of each of your temporary demountable structures. You will also want to consider non-structural elements, like hanging decorations and suspended electrical wiring.
Two-Tier Warning System for Wind Management Planning
The Institution of Structural Engineers provides excellent guidance for wind management planning in their Temporary Demountable Structures guide. They recommend two levels of warning for each temporary structure based on how close wind speeds get to the wind gust rating for that structure.
The “Level 1” warning would occur when wind speeds reach 75% of the wind gust rating for the structure, provided there is “an increasing general trend of recorded wind speed”. This is when preventative action could be taken. For instance, if erection of the structure is in progress, you might decide to delay the build. At this level, event staff should be put on alert that further action may be required.
The “Level 2” warning is triggered when wind speeds reach 90% of the wind gust rating for the temporary structure – again, in conjunction with “an increasing trend in wind speed”. At this level, you would implement the actions prescribed in your wind management plan. For example, you may secure the site to prevent access.
Again, taking temporary fence as our example, this table shows the two alert levels for 6’ high fencing based on the wind gust rating of 62 km/h:
List the Recommended Actions at Each Wind Force Rating
Now that you have documented the risks for each temporary structure at different wind velocities, you can devise an action plan.
The actions recommended in your wind management plan are intended to eliminate or mitigate the wind-related risks you have identified. Here are some example of prescriptive actions you might include in your plan:
- Placing staff on alert
- Postponing construction of a temporary structure until wind speeds reduce
- Checking stakes, anchors and ballasts to ensure they are still in place
- Securing hanging fixtures against swinging
- Removing or securing anything that could become airborne
- Evacuating the area
You may consider having distinct plans for each phase of your event. For instance, a wind management plan for your “operational phase” (i.e. during the event) is likely to look different from the plan for your “build phase” (i.e. pre-event) or “teardown phase” (i.e. post-event). The people present on site and the risks involved may differ between phases, so be sure to take all stages into account.
Other Considerations for Wind Management
Once you’ve identified the wind speeds at which warnings should be triggered, you’ll need to decide how you will measure and monitor wind speeds. Typically, this would include monitoring weather forecasts for the area from the beginning of the construction phase all the way through teardown. Your wind management plan may also account for measuring wind speeds at the site using anemometers placed as close to the temporary demountable structures as possible. The anemometers should be checked regularly when wind speeds begin to approach the warning levels you’ve established.
You will also need to assign responsibility for the wind management plan. As you write your plan, try to answer the following questions:
- Who will monitor wind speeds?
- Who is responsible for alerting staff when winds approach potentially dangerous speeds?
- Which staff members need to be alerted?
- Who takes the actions prescribed in the plan? Does this change depending on the phase of the project (i.e. build versus operational)?
Prevention is Paramount
Finally, prioritize prevention. Prevention is the first step in managing any kind of risk, and it should receive the appropriate amount of attention in your wind management plan.
Consider having a documented standard for demountable event structures as they pertain to wind. This might include a standard for minimum wind gust ratings for any temporary structures. For instance, you might require all temporary fencing on site to be rated for wind gusts of at least 62 km/h, per our example. This provides clear guidelines for any event staff who are responsible for procuring temporary event structures.
You may also develop a policy that prevents the use of certain types of temporary structures if wind speeds are forecasted to exceed a pre-determined level. As an example, Santa Clara University prohibits the use of tents for outdoor events if wind speeds are forecasted to exceed a Beaufort force of 5.
You can work with your contractors and suppliers to take preventive measures that improve the stability of your temporary structures. There are likely simple things you can do to make your demountable structures less susceptible to wind gusts.
To illustrate, the below table shows how basic solutions like sandbags can increase the wind gust rating for a line of 6’ high temporary fence. It’s important to understand that wind ratings for temporary solutions should always be used as guidelines only, as the unique characteristics of your site may have an effect.
Note that this table reflects wind gust ratings for temporary fence with no hanging materials. The addition of any hanging materials – such as banners, screening, sound blankets or signs – will increase wind load and significantly reduce the wind gust rating.
Sample Wind Management Plan for Outdoor Events
We’ve developed a wind management plan template to help you get started. The template can function as a standalone plan, or be integrated into your existing event management plan. Click the button below to download the PDF template.
More Information About Wind Safety
Interested in knowing more? At Modu-Loc, we’re devoted to understanding the impact of wind on the safety and stability of our temporary fencing. The following blog posts are great resources on the subject:
We’re here to answer any questions you may have.