Satellite images can make it easier to get around when you’re using apps like Google Maps, but researchers at NASA’s Jet Propulsion Lab and the UK’s University of Bath believe advanced satellite imagery can also be used for a more critical purpose: analysing structures like bridges for tiny movements that could be signs of potential collapse.
When it comes to infrastructure projects like bridges, cities and municipalities strive to conduct regular inspections and perform preventative maintenance. This upkeep, however, requires major investments of both materials and manpower, and quite often structures fall by the wayside until something catastrophic happens.
In recent years, the rise of reliable cellular and wireless data networks have allowed for remote monitoring of bridges where sensors are installed and autonomously report back information about signs of movement which can be a reliable indicator about the health of a structure. But those sensors don’t tell the whole story, and can only detect problems on a bridge if they happen in areas where the sensors have been specifically installed.
Covering every bridge from head to toe in sensors just isn’t financially feasible for most cities—which is where recent advancements in satellite imagery come into play. Using a series of high-res radar images of a bridge taken from space over a period of time, researchers at NASA and the University of Bath were able to create a detailed 3D model of the structure, accurate to within a millimetre of the real thing. The researchers then analysed this model with an algorithm they developed to detect undesired movement and even warping across the entire structure—not just random points monitored by a handful of sensors.
In August of 2018, a section of the Morandi Bridge in Genoa, Italy, collapsed, killing 43 people. The researchers applied their modelling techniques and algorithm to 15 years' worth of satellite imagery that included the bridge and found that it did show unusual signs of warping and deformation several months leading up to the collapse.
This research suggests the technique could work in real-world situations, and while the approach wasn’t in place to help the people of Italy, it does have the potential of preventing similar tragedies from occurring elsewhere in the world. Because it’s all reliant on software and satellite data that’s relatively accessible, monitoring structures like bridges could be done autonomously and by a single organisation. Municipalities could be alerted when warning signs start to appear on a structure months before any physical damage becomes noticeable, giving them enough time to make more detailed assessments and repairs before tragedy strikes.
The researchers also suggest the technique could be used to monitor construction projects or, more specifically, existing buildings and structures nearby that could be affected by the work and machinery rumbling through all day long. It could even keep an eye on projects happening underground, such as tunnel boring projects, ensuring that surface structures aren’t being affected by the work, or the giant holes being created beneath them.