A wind forecasting system to increase safety on Calgary construction sites
Every year wind gusts blow construction materials from buildings in Calgary, endangering the work site, nearby pedestrians and motorists, and the façades of adjacent buildings. The City of Calgary engaged us to develop a tool to help construction firms manage this risk by delivering site- and height-specific wind gust forecasts.
Located on the eastern edge of the Rocky Mountains, the City of Calgary is vulnerable to strong wind gusts that can present serious risks to people and property around construction sites. Gusts can blow materials off of tall structures, sending them either into adjacent buildings or directly to the ground, where they may harm workers, equipment and the public. Gusts can also jeopardize crane lifts; create wind loads on tarps, hoardings or other coverings; and exceed safe operation thresholds for cranes, scissor lifts and swing stages.
To reduce these risks, construction managers tend to secure tools and materials, increasing costs and reducing efficiency. Standard weather forecasting tools can predict wind, but they don’t offer much specificity about the timing and intensity of gusts, nor do they shed light on how the wind will affect particular structures at specific heights. Because of these shortcomings, standard forecasting tools weren’t doing enough to help construction managers and workers maximize both safety and efficiency at their building sites.
The City engaged us to create a tool that would provide the detailed information the construction industry needed: site- and height-specific wind gust forecasts that offered advance warning of the timing and intensity of adverse wind conditions.
We drew on expertise from multiple service sectors within RWDI to develop Calgary’s gust prediction system, including our mesoscale meteorology team, our high-rise structural wind engineering group and our environmental software services group. These three groups worked together to design and develop an automated forecasting system to meet Calgary’s wind challenge.
In order to be useful for the construction industry the gust forecast needed to be based on high-quality, accurate information. The information also needed to be accessible and presented in a format that construction site personnel could interpret and act on as easily as possible.
High Quality, Accurate Weather Forecast
The system incorporates five key inputs:
- two numerical weather forecast products automatically downloaded several times daily from the US-based National Centers for Environmental Prediction (NCEP);
- two custom-configured Weather and Research Forecasting (WRF) models; and,
- hourly observation data from over 100 meteorological stations in Western Canada.
The system automatically ingests meteorological station data and weather forecast products from NCEP into our high-performance computing cluster. This data is then used to initialize our two custom-configured WRF models that cover the City. The system uses an ensemble approach to determine the maximum wind speed from all four models, and uses statistical turbulence wind gust factors to determine site- and height-specific wind gust values. The forecast is updated hourly as new forecasts are downloaded or generated.
Ease of use
Once the data is processed and height-specific wind gust values are produced for the participating construction sites, users can access the forecasts using standard desktop internet browsers, tablets or smartphones. The system can also be configured to deliver the forecast by email to a list of recipients at predefined times. It can also send wind gust alerts via email or text message whenever conditions are predicted to exceed user-specified thresholds.
The system was released in August, 2011, and has been helping construction managers increase the security of their work sites ever since. It is currently providing wind gust and weather forecasts for over 100 sites in the City of Calgary, sending over 1,000 user-requested emails and text messages to clients daily. The tool has been recognized by the Calgary Construction Association for its ease of use.