Wind monitoring is key during all life cycle stages of a bridge, from design and construction to operation and maintenance. Bridges are typically exposed to strong wind currents hitting them perpendicularly, and their sheer size results in very high mechanical loads induced by the wind. Even if a bridge is properly designed according to wind conditions, the wind may also pose a risk for vehicles.
Wind loads are a very important aspect of structural design, and monitoring is the only way to get a detailed and site-specific profile of wind conditions. This allows structural engineers to specify and design a bridge structure that is well-suited for the intended project site.
The case of the Tacoma Narrows Bridge, which collapsed in 1940, is perhaps the best-known example of how the wind can destroy a bridge with a poor structural design. The bridge showed drastic movements in response to the wind. The first time it was exposed to a 42-mph wind, it twisted until it collapsed. This was just a few months after construction.
Although nobody was killed in this accident, the material losses were significant. This case demonstrates the importance of having a detailed wind profile of the public bridge site before proceeding with its design and construction.
The risks that are present during bridge operation are compounded during construction since the structure is work in progress. Often, it does not have the mechanical strength as designed until completed.
Although construction activities can be programmed based on weather forecasts, the precision achieved is very limited. In addition, it may be difficult to justify missed deadlines due to unfavourable weather, potentially leading to project disputes. A web-connected weather monitoring station is far superior to weather forecasts, providing various advantages:
Wind monitoring also allows the project to be scheduled during a season of the year when wind-related risks are minimal. Since a detailed wind profile has already been gathered during the design phase, the months where average wind speeds are low are well-known to the project developer.
The case of the Tacoma Narrows Bridge is a drastic example. But the wind can make a bridge dangerous even if it is nowhere close to collapsing. Vehicles such as SUVs and trailers are prone to turning over when exposed to harsh winds from the sides. The wind-facing area is large, and their centre of mass is higher than that of other vehicles.
Bridge movements may also pose a risk for drivers: Under harsh winds, some degree of structural deformation is normal and accounted for by design engineers, but the risk of causing an accident remains.
Once a bridge has been built, WINDCRANE can continue delivering live data to the public authority responsible for the bridge. The same features that alert construction managers when dangerous winds are detected can be used to alert the corresponding authorities, who may block public access to the bridge until wind speeds have returned to safe values.