Imaging a safer future - No 23 - May 2020

Mapping Bridge Undersides with U3S

Land or Sea - NEXCO Will Be There


U3S uses a dual-camera connection to take visual and IR pictures at the same time. The visual and IR cameras are positioned on a cart, boat, tripod, or hand-held harness to adapt to various types of access. No matter what is beneath that bridge (with the exception of canyons) we will be able to capture it. For example, many bridges carry roads over bodies of water. U3S can still map from a boat or barge with stabilizing equipment and proprietary image stitching techniques. When crossing overland, the terrain below is often rugged, but U3S can still be carried with a harness on-foot. Best of all, when the terrain is flat, we can capture the data on a cart, which makes both fieldwork and post-processing very fast.


When all is said and done, U3S can effectively capture entire bridge surfaces from the inside out (as mentioned in the previous article on the Pearl Harbor Memorial Bridge). Additionally, our past projects and case studies have shown that the resolution and crack detection capabilities of U3S far outshine those of current drone imaging. With stable and high-definition shots, we are able to map cracks with 0.1mm width in ideal conditions, 0.3mm widths in most other conditions. The average UAS system will be able to find cracks at a minimum of 1mm, and this does not support the AASHTO 0.3mm threshold between insignificant and moderate cracks.

Differing Calls on Bridge Condition in Florida:

How Structural Assessments Can Reach Different Conclusions


One possible explanation is the high degree of subjectivity in past and current inspection practice, which can lead to potential concerns going unchecked. While the response demonstrated upon discovery of the cracking and corrosion was phenomenal, we can clearly see how significantly such measures impact the public and the owners. We believe this case serves as a representative example of how pre-screening structures with rapid NDE technology can identify areas of concern with greater objectivity. By doing so, costly emergency response measures can be reduced.


Generally, these types of deficiencies do not occur overnight, but they are difficult to detect in early stages and document by hand. We believe it would highly benefit owners to implement inspection technology that preserves data on the entire structure. Imaging and mapping technology have the capacity to map scaled deficiency locations onto 2D or 3D records of the structure (in the form of images, CAD, or digital twins).


As the use of scanning technology expands in practice, we hope to see a steep reduction in the occurrence of critical findings, and utilize better prediction models to find and address corrosion in its early stages.

To review our previous newsletters, conference presentations, and technology, please follow the links below:


Imaging a safer future - No22 - April 2020

Imaging a safer future - No21 - March 2020

Imaging a safer future - No20 - February 2020

Imaging a safer future - No19 - January 2019

Imaging a safer future - No18 - December 2019

NEXCO - West USA, Inc.
8300 Boone Blvd., Suite260
Tysons Corner, VA, 22182

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