YellowScan has published a case study showcasing the application of its Vx20-300 UAV LiDAR technology by L’Avion jaune for assessing rockfall risks on roadways.
Identifying the Challenge
Commissioned by the Departmental Council, L’Avion Jaune, in collaboration with Ginger CEBTP, a geotechnical consultancy, undertook a extensive risk assessment of rockfall threats to their road infrastructure. The primary objective was to devise effective preventive strategies to safeguard motorists.
Natural erosion of limestone cliffs can lead to landslides and rockfalls, displacing meaningful amounts of debris that pose risks to the roads situated below.
Risk management relied heavily on trajectographic analysis, which involved simulating the descent of rock masses from cliff tops to valley floors. This approach aimed to assess the potential risks and enhance the design and placement of rockfall barriers.
To effectively mitigate these risks, a 3D modeling study of the cliffs adjacent to a busy roadway was crucial. The site measured 200 meters (655 feet) in height, 300 meters (980 feet) in width, and extended 2.5 kilometers (1.5 miles) in length.
Trajectography of landslides and rockfalls
Proposed Solution
Given the challenging terrain and dense vegetation, customary soil mapping techniques were inadequate. Consequently, L’Avion Jaune deployed the YellowScan Vx20-300 to survey the cliffs and generate a Digital Terrain Model (DTM) through meticulous classification and filtering of the laser data.
“For surveying such environments, drone LiDAR is unparalleled: it significantly enhances safety and efficiency. The Vx20-300’s five echo capabilities allow it to penetrate vegetation effectively, capturing ground data to produce an accurate DTM, thus providing geologists with essential 3D maps for risk assessment and decision-making,” stated Benjamin Pradel, Aerial Survey Project Manager at L’Avion Jaune.
Outcomes Achieved
The adaptability of L’avion Jaune’s approach facilitated the rapid acquisition of a dense point cloud and the creation of a precise and comprehensive DTM in under three days.
- Point Density: 100 pts/m² (10 pts/sqft)
- Precision (X, Y, Z): 5 cm (2 in)
- Advantages: Access to hazardous areas, ground mapping beneath vegetation, and swift deployment
Mission Parameters
The mapping of the entire site required four flights, each lasting fifteen minutes.
These operations were conducted at dawn to minimize road traffic. Control points near the road were surveyed using differential GPS (DGPS).
Data processing took approximately two days, involving trajectory corrections, alignment of flight paths, and point cloud classification.
- Number of Flights: 4
- Area Covered: 75 hectares (185 acres)
- Total Operation Duration: 6 hours (including flights, quality checks, and DGPS point collection)
- Flight Speed: 5 m/s (11 mph)
- Flight altitude: 60 m (200 ft)
- Equipment Utilized: YellowScan Vx20-300
- Digital Terrain Model of the surveyed area
- LiDAR point cloud generated by YellowScan Vx20
