An Icon Meets the Future

Feb. 1, 2024
Drones and AI help preserve a historic bridge

By Barritt Lovelace, Contributing Author

The following story outlines a project that was a finalist at Bentley’s 2023 Going Digital Awards in Infrastructure in the Bridges and Tunnel category. The awards were announced at Bentley’s Year in Infrastructure conference in Singapore in October, and this was one of 15 projects that were recognized for the Founders’ Honors.

Built in 1926, the Robert Street Bridge stands as an icon of downtown St. Paul, Minn., and it offers the public a thoroughfare that spans the Mississippi River.

The bridge connects the city’s downtown with the west side, its rainbow arches and concrete medallions a centerpiece of the Moderne style. The concrete arch bridge serves as an example of the city’s history and longstanding tradition.

To maintain this piece of state history, the Minnesota Department of Transportation (MnDOT) sought out the team of Collins Engineers, Inc. and Michael Baker International to ensure this icon could last well into the future.

The team’s familiarity with the newest bridge inspection technology was crucial to the project. We made the Robert Street Bridge the focal point for a new workflow, making significant use of unmanned aircraft systems (UAS), digital twins and artificial intelligence to move the bridge inspection field forward and improve project outcomes.

The Robert Street Bridge serves as an important focal point for St. Paul. It operates as a main corridor of Minnesota State Highway 3 and carries travelers across the Mississippi River.

Added to the National Register of Historic Places in 1989, the bridge stands out for its sheer size when compared to other structures of this type. Because of this scale, the potential for hundreds or thousands of potential inspection findings makes traditional inspection a detailed and time-consuming process.

This historical landmark shows its age, so MnDOT partnered with the project team to inspect the bridge and provide a bridge management plan.

To aid in the inspection and cataloging of potential issues, we used automated drones to provide a large-scale digital twin of the bridge.

The 3D-scan application allowed our team to quickly and accurately collect data that was processed into a digital twin of the bridge.

This virtual replica allows internal engineers and external stakeholders an interactable reproduction of the full-size bridge available on the cloud. It also offers granular photo quality and detail, as the drone’s camera can pick up on small defects such as cracks or other points of interest.

However, we took this technology and advanced it one step further, making use of artificial intelligence (AI) to analyze the digital twin and automate finding, quantifying, and communicating the concrete crack information to our inspectors.

This “pre-inspection” of the 3D model offers a baseline of information on cracks and defects. The model provides thousands of datapoints that off-site engineers are able to review without ever stepping foot on the bridge.

While nothing can truly compare to an in-depth physical inspection of the bridge by trained professionals, this digital twin provides an estimated 80% of the information inspectors are looking for prior to field work.

Technology reduces the time required for field inspections between 30% and 40%. It also creates a clear plan of action for the on-site inspectors, allowing them to corroborate potential questions and double-check any false positives that may arise from the initial viewing.

A digital twin also offers the chance for engineers or stakeholders who may be physically unable to inspect the structure on-site to still provide their expertise and guidance. This widens the potential pool of knowledge that can be lent toward a given project.

The benefits of this digital model and AI data collection extend beyond the information offered to our on-site engineers, as well.

By making use of this technology and reducing the time needed for physical inspection, we’re able to improve safety for our employees and the public, shortening lane closure times and putting fewer staff at risk for potential accidents. This also offers a monetary savings to the public by cutting down on vehicle backups or slowdowns.

Once the inspection is complete, the digital twin is shared with other stakeholders, as well as the client. Instead of referencing issues or defects through pictures and writing, engineers can visually pinpoint the exact areas that require attention and share them with others in the 3D virtual space.

This allows for immediate feedback from team members following our work, including design and construction professionals, ensuring accountability throughout the process. Additionally, Collins can expand our education and outreach programs through these models across a variety of professional skillsets, ensuring all stakeholders are fully aware of our findings in an easy-to-digest manner.

Once the design phase is completed, the digital twins can be shared with potential contractors, enabling more accurate cost estimates and ensuring our client has the most precise information available throughout the bridge’s rehabilitation.

While we’re just getting started on integrating this technology into our overall workflow, Collins Engineers already has experienced success using UAS and AI technology.

The Robert Street Bridge project exemplifies that success. In October in Singapore, I delivered a presentation at Bentley Systems’ 2023 Year in Infrastructure and Going Digital Awards about how the software we used was integral to the project.

When you attend a conference such Bentley’s, one can’t help but ask: What does the use of this technology look like in the future?

During my presentation, I highlighted the fact that, while the Robert Street Bridge is a large, multi-faceted project, this workflow can be adapted and streamlined for almost any kind of structure. This includes smaller bridges, retaining walls and sign structures, among others. And this type of technology will continue to grow within the inspection and construction field.

I also pointed out that, while stakeholders needed time to learn how to use the new technology, everyone involved saw the benefits of AI within these models. Using AI may seem like a novelty today, but it will soon become a must-have for clients across the world — probably sooner than you think.

While Collins Engineering is only beginning to scratch the surface of what this disruptive technology can provide for our industry, we owe it to our clients and the public to push the limits of AI, machine learning and UAS. We need the highest quality inspection data and workflows available, and this technology delivers. RB

Barritt Lovelace is the vice president of UAS/AI/reality modeling at Collins Engineers, Inc.

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