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Still Hanging from Ropes for Your Bridge Inspections?

U.S. DOTs are using digital twins for remote bridge inspections, ensuring the safety of their workers and improved visibility.

3D / VDC Infrastructures
Published: 08/04/2021

One of the biggest challenges for our transportation agencies is how to conduct accurate, timely and safe bridge inspections. Bridges have long lifecycles—up to 75 or 100 years. It’s important to track structural changes over time. Maintaining bridges is key to ensuring public safety, and bridge owners and engineers need to perform inspections to determine structural integrity to plan for maintenance, rehabilitation, and replacement of those bridges. 

However, traditional visual inspections that take place on-site are labor intensive, can require expensive equipment, often require lane closures that create inconvenience for travelers, may present safety risks, and can be inaccurate and error prone. 

National bridge inspection standards in the U.S. require additional data inputs and layers of complexity. And in today’s COVID environment, maintaining social distancing and ensuring safety for employees and the public can present additional challenges. Recently, though, roadway agencies have been using technology to perform bridge inspections remotely while maintaining the safety of their employees. One of these technologies is digital twins, which is the digital representation of a bridge, as well as the engineering information that allows teams to understand and model its performance. 

At Bentley, we are dedicated to helping our users implement digital twins, helping them create computer models that replicate what’s physically out there in the field.


Digital twins allow inspectors to immerse themselves in the model of a bridge structure without being physically onsite. Inspectors conduct inspections using a digital twin of the asset, along with immersive inspection capabilities in Microsoft HoloLens2, which helps users get an understanding of what is actually happening in the field without having to be there. This capability not only reduces the time required in the field, but it also makes the inspections more efficient, safer, and less costly. Some engineers that we work with think that they will be able to perform in the office 90% of what traditionally had to be done in the field.

Bentley’s infrastructure is built on Microsoft’s Azure platform. Our digital twin technology combines engineering data, reality models, and inputs from Internet of Things (IoT) connected devices, such as drones or sensors. All these components connect physical assets in the real world with their digital counterparts, providing a holistic view of assets aboveground and below ground. 

So, instead of trying to find and determine cracking or corrosion through photographs, digital twins allow owners to track these types of historical changes with exact measurements. 

By using drones to assist in inspections, some U.S. agencies that we work with have saved as much as 40% of their costs. With a digital twin, they can see the change over time and have a comprehensive view of the bridge, including seeing past inspections laid on top of the current data, which can improve efficiency and help predict the future.


One example is the Minnesota Department of Transportation (DOT). The state currently has 20,000 bridges, all of which need to be inspected regularly so that the state can properly maintain them over their lifetime and find out what they need to do to replace them. Jennifer Wells, state bridge inspection engineer at the Minnesota DOT, explained that, “Most of those engineers don’t go out in the field much so it’s hard to relay through close-up pictures and trying to explain to them what I’m seeing.” There was a great opportunity for the Minnesota DOT to use drones and Bentley software to complement and augment standard and in-field inspections. They could review the data from these inspections quickly and easily from anywhere. When engineers look at time-lapse comparisons of detailed changes, they can annotate specific areas of concern and designate anything that needs to be specifically reviewed in the field. Field crews can see all the inspector notes right on the structure, which is more visual, accurate, and efficient. All these capabilities are geared toward saving costs, avoiding risks, and reducing the time required for inspections. 

One of the biggest advancements is a reality mesh, the visualization for a digital twin that gives yet another dimension to our understanding of the infrastructure and surrounding topography. The photos, videos, and data captured by drones can be used to produce a high-resolution reality mesh of a bridge. “These images can get right down to the cracks themselves we can measure the width of them, not just the length,” Wells said. “They’re that detailed.” Using reality meshes for inspections can significantly decrease the amount of time inspectors have to be on and around structures in the field. 

A digital twin provides flexibility. DOTs can conduct more in-depth inspections without having to schedule expensive equipment and labor. They can apply digital twins over many large, complex, or signature bridges, which can lead to significant savings, while increasing safety and providing richer visualization.

Utilizing digital twins to collect, process, store, and analyze large amounts of data can reduce time and costs while increasing quality of inspections. If it could reduce the overall inspection expense by 10%, that would be a huge win—and we’re talking about potentially saving several times that amount in overall savings. With the Microsoft HoloLens2 and the Azure Remote Rendering capabilities, we’re able to see accurately, truly geometrically, the impact of changes over time. The technology can improve safety for inspectors and the public at large and help preserve bridge infrastructure into the future. The more that we work with this, the more potential that we are identifying. This technology can make bridge inspection roles that much more accessible, enabling diversity in execution while also providing the general public with more assurances that the entire extent of every structure is being inspected.

This isn’t science fiction anymore. It’s real, it’s here, and it’s making an impact on our  bridges right now. Let’s put the ropes away for good.

Want to see this new technology in action for yourself. Check out this:


Author: Dan Vogen, Vice President, Road & Rail Asset Management, Bentley Systems



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