Phil Buchan sheds light on Network Rail and Cyberhawk’s project to trial drones for large structural inspections

The structures asset management team for Network Rail’s London North Eastern & East Midlands route was seeking a more efficient way of conducting inspection for assessment on large structures, for instance, viaducts.

For several years, Network Rail has worked with Cyberhawk Innovations, a leader in inspection and survey using unmanned aerial vehicles (UAV), otherwise known as drones. To date, this has mainly involved the inspection of assets such as overhead line equipment and rail stations. Understanding how UAV technology works, and the major benefits on offer, Network Rail appointed Cyberhawk to trial the use of drones for viaduct inspection.

The benefits that Cyberhawk wanted to prove from this trial was that UAV inspection, compared with the traditional rope access inspection techniques, was quicker, more cost-effective, reduces safety risk to personnel and reduces the need for track possessions.

Project planning
Prior to the project commencing, Cyberhawk created a method of data capture which ensured the team would capture the detailed level of coverage required. This involved mobilising additional members of the team to act as spotters when conducting the overhead element of the inspection and using a total station with reflectorless measurement to locate features on the asset, thus increasing the quality of data captured.

Because there were a number of stakeholders and other contractors involved, Cyberhawk was required to liaise with these parties to ensure appropriate flight permissions were secured and to provide notification that UAV inspection was happening. With over ten years’ experience in this area, Cyberhawk’s track record was incredibly useful at this stage.

The project commenced late 2017, with two viaducts initially being trialled. This was to identify any potential issues which may have arisen, so these could be addressed at an early stage and avoided during later inspections.

Cyberhawk’s team of pilots and inspectors have inspected five arch viaducts to date, including Chesterle- Street in County Durham and the Grade 1 listed Royal Border Bridge in Berwick-upon-Tweed.

Proving the benefits
The team’s collective aim was to demonstrate that a UAV inspection for assessment was faster, cheaper, safer and generally more efficient, however did not compromise on data quality. The ultimate aim, in fact, was to demonstrate these efficiencies while actually improving the quantity and quality of data collected.

Faster – Rope access would typically be used for large, high structures and would take many weeks per viaduct. An additional mobilisation would also be required to gather measurable data. A key objective was to reduce the time required per inspection and obtain all necessary data on the same mobilisation, using one team.

The UAV inspections have taken, on average, just two weeks per viaduct with all data collected in one mobilisation. This is a time saving of at least 50 per cent.

Cost effective – longer inspection times usually mean higher costs. By reducing the time taken per inspection, this would bring down the cost. Because of the speed of the UAV inspection, the cost savings are estimated at 50 per cent. The inspection was also conducted with a single team, so no doubling of contractors was required.

Reduced safety risk – rope access involves dangling at height, often in poor weather conditions, in the dark and in close proximity to a track. Using a UAV to conduct an initial inspection immediately removes the need to send a person into a hazardous environment. The results from these inspections demonstrated a UAV is more than capable of completing the job.

Minimised track possessions – to reduce the risk to safety, inspection work is usually undertaken during a track possession however this means operational downtime for the train service. Cyberhawk wanted to highlight how UAVs avoid the need for possessions thus causing less disruption to scheduling. The UAV inspection proved that no track possessions were required.

High quality data – Network Rail also wanted a solution which provided extremely high quality, detailed data which could be used in a variety of formats and for different purposes. The high definition images collected by UAV were a vast improvement on the usual photographs taken, where views can be limited to where the engineer can see and reach. Better quality data allows asset managers to make better, more informed decisions.

As well as the high-quality photographs, which delivered a 360 degree view clearly showing all defects, Cyberhawk also provided Network Rail with 2D elevations, 3D models and cloud point surveys from data collated during the UAV inspections. This meant an additional benefit of avoiding the need for a separate dimensional survey.

Project feedback
Terry Donaldson, scheme project manager at Network Rail said: “As well as being cost effective, this innovation has reduced the need for track possessions, track access and roped access, reducing safety risk. The quality of the information our asset engineers have received has also been much better than what can normally be produced with standard inspection techniques.”

The trial demonstrated that UAVs have excellent potential as a tool for inspecting arch viaducts in particular, with further UAV inspections being planned. It is recognised that aerial inspections fit into the wider inspection programme, in that they do not replace an engineer with tools undertaking repairs. However, obtaining better imagery allows asset engineers to locate areas of concern and target those first.

The operator is already planning to roll out this inspection solution across thousands of additional large structures.

Phil Buchan is Commercial Director at Cyberhawk Innovations. Cyberhawk is the world’s leading engineering company using unmanned aerial vehicles (UAV) for aerial inspection and surveying, and a pioneer in the development of innovative visual asset management and maintenance software. Cyberhawk has completed more than 25,000 flights and worked in over 30 countries. As well as the rail and infrastructure sectors, the company also operates in utilities, oil and gas and renewables.