DRONE SURVEY OF DRAINAGE CASCADE
2025
Background
Client: National Highways, Yorkshire & North East Region
We were engaged by National Highways (NH) under the TST contract to undertake a detailed topographic and structural survey of the A628 Longside, Woodhead Pass drainage cascade.
Location: A628 Longside, Woodhead Pass, Yorkshire
The site forms part of a critical drainage structure located on a steep hillside within a Site of Special Scientific Interest (SSSI), requiring the adherence to strict environmental and operational constraints.
Challenges
The existing cascade structure was exhibiting signs of deterioration, with misaligned and dislodged slabs creating instability and posing operational risks. Direct access to the structure was unsafe for surveyors due to steep slopes and loose material, preventing traditional ground-based survey methods.
National Highways required an accurate topographic survey to assess defects, measure levels, and identify slabs needing realignment, while ensuring survey operations did not compromise safety or environmental protections. High winds during our initial field visit further constrained the use of aerial platforms, necessitating additional mobilisation. The survey had to be completed under a lane closure for safe access to the area. Prior to commencing on site we had to comply to National Highways guidance for flying a drone. The site is a SSSI, and vegetation clearance was undertaken by National Highways under specific environmental guidelines for a SSSI prior to MHLS attending site.
Tools & Technology
- UAV LiDAR and high-resolution imaging systems
- Terrestrial laser scanning
- Data processing and point cloud integration using industry-standard software for geospatial analysis
Solutions Devised
To address the safety and access limitations, we completed the survey remotely using LiDAR-equipped drone systems and a terrestrial laser scanner positioned at the roadside verge above the cascade. This hybrid approach enabled comprehensive data capture without requiring our surveyors to enter hazardous areas.
Deliverables: Malcolm Hughes was tasked with producing a full topographic and condition survey of the drainage cascade, including:
- 3D point cloud data
- Orthophotography and high-resolution imagery
- Detailed level data and defect mapping
The deliverables were used by National Highways engineers to inform remedial design and maintenance planning.
Summary
Our approach delivered a precise, high-density dataset that allowed accurate modelling of the cascade structure and identification of all areas requiring remedial work. The survey was completed safely under controlled lane closure conditions and in full compliance with SSSI environmental guidelines. The project demonstrated Malcolm Hughes' capability to integrate drone and laser scanning technologies to deliver safe, efficient, and high-quality surveying solutions for complex infrastructure environments.
"The issues with this historic stone structure were substantial and we needed to quantify , reference and identify the problems to develop a quick repair intervention. Malcolm Hughes were commissioned to carry out a remote survey because of the access difficulties using their drone and remote station methods to scan and provide a 3D image of the structure. The information allowed us to quickly to quantify the issue develop a solution and develop a successful intervention.
The 3d Photogrammetry was an incredible image where we could manipulate the image to look at the feature where we could see every blade of grass!!!"
Gareth Lewis, Principal Engineer , OD YNE P&D Asset Management National Highways
