When it comes to effective emergency and disaster response, drones (also referred to as UAV or RPAS) are an effective way to capture geo-accurate mapping data.
By using fixed-wing drones, such as the senseFly eBee X, professionals on the ground can remotely launch and collect the data they need quickly and safely over small and large areas alike.
Drone mapping is especially valuable in situations where ground access is obstructed or otherwise impossible due to safety and logistical concerns.
Such was the case on August 14, 2018, when the Morandi Bridge, located in Genoa, Italy, suddenly collapsed.
Tragedy strikes Italy
The structural failings of the Morandi Bridge caused vehicles crossing to plummet more than 150 feet. The incident claimed the lives of 43 people and caused significant damage to the surrounding area as well as to the riverbed below.
While the 3,878-foot bridge served as an important commercial link between France and Italy, it is the tragic loss of life that underlined the need for innovative solutions to help define better emergency response protocols.
Following the Morandi Bridge collapse, representatives of Nucleo SAPR VVF—the drone division of Italy’s National Fire Corps—CIMA Research Foundation and Environmental Protection Agency of Aosta Valley (ARPA VDA)—carried out an in-depth inspection and survey of the site.
To help with this initiative, Nucleo SAPR VVF used a fleet of drones operated out of seven VVF sites and employed by 70 pilots across the nation as ‘first-eyes’ on emergency situations and to inspect and survey the sites of emergencies post-disaster.
In December 2018, a trial assessment of the damage inspection project was conducted. The goal of this trial assessment was to provide rescuers with a defined operational protocol for assessing future emergency situations using drones and to improve the accuracy of the photogrammetric outputs derived from the drone imagery.
The drone mapping project, which was conceived and facilitated by Umberto Morra di Cella, RPAS unit head of the ARPA VDA and supported by senseFly, took place at the site of the Morandi Bridge collapse.
“As we look to expand the use of [drones] across the nation, it is crucial that we develop and continue to improve our operating procedures so that this technology helps us respond to disasters as effectively as possible,” said Franco Feliziani, manager of VVF’s drone teams across Italy. “What the Genoa project allows us to do is to fine-tune how we work in terms of optimizing and streamlining our on-the-ground workflows”.
Surveying the situation with drones
For the drone mapping assessment, a senseFly eBee X fixed-wing drone carrying a senseFly S.O.D.A. 3D camera was flown at a height of 120 meters over a rectangular 32-hectare section of the site, which spanned the bridge’s ruins and the dry riverbed.
The senseFly S.O.D.A. 3D camera was selected for its ability to change orientation during flight and capture three images (two oblique and one nadir). This is important in vertically-focused environments, where its wide field-of-view ensures excellent 3D-mapping results.
“As we look to expand the use of [drones] across the nation, it is crucial that we develop and continue to improve our operating procedures so that this technology helps us respond to disasters as effectively as possible…” – Franco Feliziani, VVF Drone Team Manager
To ensure the geo-accuracy of the maps and 3D models the drone images helped produce, the eBee X drone was flown in high-precision RTK mode.
This large-coverage flight was followed by multiple multi-rotor drone flights, flown at a height of approximately 30-100 meters above the ground.
This was done to help capture the highest resolution imagery possible of a smaller area of the bridge’s ruins (particularly in the river bed, which posed a future flood risk).
Following the data collection flights, ARPA Aosta Valley and senseFly staff independently processed the images collected from each drone flight’s using professional image processing software Pix4Dmapper.
This helped create 3D digital datasets of each flight, which were then combined into one overarching, geo-accurate digital representation of the Morandi bridge site.
But it’s not just loss of life and damage to infrastructure that requires innovative solutions and defined disaster response protocols.
Events like the Morandi Bridge collapse can have a significant impact on the environment and bring about new risk scenarios, thus requiring regular updates of site conditions.
“The bridge collapsed in the Polcevera River and modified the flow conditions and increased the risk of flooding to the surrounding urban area,” said Luca Ferraris, head of CIMA Research Foundation for the Italian National Department of Civil Protection. “This made it necessary to map the hazard map evolution progressively and support local authorities in developing its emergency plans.”
While access to the temporal data was certainly important, Ferraris explains that the accuracy of the data played an even more vital role.
“The accuracy assessment of the photogrammetric process is perhaps the most important aspect because we need to be sure that the data we capture is reliable enough to help inform the civil protection process”, said Ferraris.
Drone diversity and the road ahead
It’s expected that the learnings gained from the Genoa project will allow Nucleo SAPR VVF to better provide its staff of drone operators a carefully defined best practice approach going forward.
“It is very important to standardize the procedure so that pilots can collect large amounts of accurate and high-resolution data,” Feliziani said. “This is especially true after an emergency situation where this work needs to be carried out quickly, safely and efficiently.”
“The accuracy assessment of the photogrammetric process is perhaps the most important aspect because we need to be sure that the data we capture is reliable enough to help inform the civil protection process.” – Luca Ferraris, Head of CIMA Research Foundation for the Italian National Department of Civil Protection
The project has also highlighted the need for a diverse range of drone mapping equipment, a consideration Morra di Cella is keen to point out.
“The combination of large-coverage fixed-wing UAVs with ultra-detailed data from smaller quadcopter drones represents a good compromise between operational needs and quality requirements,” said Morra di Cella. “Moreover, the RTK RPAS can significantly reduce ground displacements of operators in unsafe scenarios.”