Case study //

360 Degree Inspection Video & 3D Digital Twin Modelling of ‘Summit Tunnel’ Vent Shaft

Category: Asset Inspection

Client: XEIAD (Part of the BES Group) for Network Rail

Date: June 23

Summary: Detailed 360 degree inspection video, imagery and digital twin 3D modelling of a 90m tall 3m diameter ventilation shaft in the Summit Tunnel.

In 2022 HexCam was asked by XEIAD to develop a drone-based method of inspecting a 90m tall, 3m diameter ventilation shaft in the trans-pennine ‘Summit Tunnel’. Constructed between 1838 and 1841 to provide a direct line between Leeds and Manchester, the tunnel is one of the world’s oldest rail tunnels and, when built, was the longest in the world. Maintaining ageing infrastructure presents unique challenges and difficult access.

The Problem

Traditional rope access methods involving descending into the shaft from the hilltop above were no longer possible due to the poor condition and remote location of the shaft head. The shaft was therefore only accessible from the track bed some 90m below; a GPS denied environment that presents challenges for most off-the-shelf drones.

Access to the track at the base of the shaft (a mile long walk along a ballasted track bed) was restricted to overnight track possessions while work was being carried out on the line and other sections of the tunnel and its shafts. A fast, reliable, lightweight solution was needed to take full advantage of the limited possession times.

The Solution

HexCam explored several technical solutions including a LiDAR guided drone and a bespoke build inspection drone. Challenges included making the drone and its payload small and lightweight yet stable enough to operate within a narrow shaft in highly variable up and down draughts and condensing water vapour.

HexCam’s extensive knowledge of DJI products and their performance characteristics helped us to build a bespoke payload, comprising a 360 degree camera and high intensity 360 degree LED lighting, that could be carried and powered by a DJI ‘FPV’ drone. The lack of GPS within the tunnel was overcome using a pragmatic and innovative workflow to override normal DJI flight height restrictions within the shaft.


HexCam delivered high quality and evenly illuminated 360 degree video allowing XEIAD’s engineers to carry out a desktop visual inspection of the shaft. We also used Twinsity’s ‘TwinSpect’ portal to present a digital twin 3D model of the shaft and the tunnel immediately around the shaft base. This model allows engineers to take measurements from and annotate the digital twin.

It has been a pleasure collaborating with HexCam on this project. Their expert knowledge in drone technologies, paired with their skilled pilots, enabled us to safely inspect this tunnel shaft. Using the drone solution that HexCam developed, enabled us to inspect this structure without having to send rope access technicians into a dangerous environment. We’re hoping that this will change the way we routinely examine these sorts of assets; not only does it stop putting staff into a dangerous environment, but it allows us to present a far richer dataset to the asset engineers that manage the maintenance of these structures.

Jonathan Jones

Examining Engineer/ Project Manager, XEIAD