Drone-Assisted Structural Examination
GeoAccess used a confined space inspection drone to examine a large culvert carrying the River Douglas beneath the railway near Wigan — a safer, faster and lower-cost alternative to scaffolding and boats.
A confined space inspection drone examined the Wigan culvert beneath multiple railway lines — nine flights and software-mapped defects cut reporting from weeks to days while keeping crews out of harm's way.
Backgrounds
GeoAccess was commissioned to examine a large culvert carrying the River Douglas beneath multiple railway lines, located 200m east of Wigan North Western Station. Historically, inspections of this structure were complex, expensive, and high-risk, often involving scaffolding or boat access with pole-mounted cameras. These methods were time-consuming and limited visibility. To overcome these challenges, GeoAccess deployed a confined space inspection drone, offering a safer, faster, and more cost-effective approach without compromising inspection quality.
Method
A two-person rope access qualified flight crew was suspended in cradles at the downstream end of the structure to hand-launch and recover the drone during successive flights. Across nine drone flights, a detailed visual examination was conducted, with particular focus on difficult-to-access areas such as undersides and recessed structural elements. The operation yielded 70 minutes of high-quality video footage, capturing the full internal profile of the culvert. Using specialist analysis software, frames were extracted from the footage and annotated with:
Defect type
Dimensions
Severity rating
This streamlined workflow replaced traditional manual image reviews, cutting report preparation from weeks down to days. The approach also ensured no critical defects were overlooked while significantly improving reporting speed and accuracy.
Innovations & Solutions
Drone technology eliminated the need for scaffolding, boats, or pole-cams.
Faster inspections completed within hours rather than days.
Reduced risk to personnel by minimising confined space entry.
Cost-effective solution with lower project overheads.
Software-enabled defect mapping ensured clarity and speed in reporting.
Results & Conclusion
The Wigan Culvert inspection was completed successfully, demonstrating the benefits of drone-based structural examinations. The project achieved time efficiency, cost savings through eliminated scaffolding needs, enhanced safety via reduced personnel exposure, and comprehensive defect documentation supporting maintenance planning.
