Global Bridge Health Check: Satellites Offer New Hope for Aging Infrastructure

A global analysis involving 744 bridges, published in Nature Communications by researcher Pietro Milillo from the University of Houston and collaborators, has identified the condition of bridges worldwide. The study indicated that bridges in North America generally show the poorest condition, followed by those in Africa.

The research team also proposed a strategy utilizing satellites to track bridge stability and detect early warning signs.

Aging Infrastructure and Monitoring Challenges

Many bridges examined in the study are nearing the end of their intended lifespan. Bridge construction surged in North America during the 1960s, meaning numerous structures are now decades old.

Current bridge monitoring methods have significant limitations. Visual inspections are costly, can be subjective, and occur typically only twice a year, potentially missing early signs of deterioration. Structural Health Monitoring (SHM) sensors offer continuous tracking but are installed on fewer than 20% of the world's long-span bridges, usually on newer structures or those already known to have issues.

Satellite-Based Monitoring: A New Solution

To address these challenges, researchers are employing space-based monitoring systems that use Synthetic Aperture Radar (SAR) and Multi-Temporal Interferometric Synthetic Aperture Radar (MT-InSAR) technology. This technology captures high-resolution images frequently over large areas and provides access to historical data.

• Detection Capability: MT-InSAR can identify movements as small as a few millimeters, which may be caused by slow geological processes or structural issues.
• Coverage: Milillo, a co-author and associate professor at UH, stated that spaceborne radar monitoring could provide regular oversight for over 60% of the world's long-span bridges.
• Cost Efficiency: Integrating satellite data into risk frameworks may lower the number of bridges classified as high-risk, especially in regions where traditional sensor installation is expensive.

The international research team included Dominika Malinowska from Delft University of Technology (TU Delft) and the University of Bath, Cormac Reale and Chris Blenkinsopp from the University of Bath, and Giorgia Giardina from TU Delft.

Malinowska noted that while using MT-InSAR for bridge monitoring is academically established, its routine adoption by authorities and engineers has not yet occurred. This study provides global-scale evidence supporting its viability.

The proposed approach integrates monitoring information from SHM sensors with satellite observations, such as those from the European Space Agency's Sentinel-1 and the NASA NISAR mission. This combined data allows for more frequent deformation measurements and updates than traditional inspection schedules, enabling improved maintenance and risk management decisions.