Requested by the telecommunication company – Arqiva, RSK Orbital surveyed Emley Moor Tower, the tallest freestanding structure in UK, which broadcasts over 10,000 square kilometers. The 3D reconstruction in Pix4Dmapper allows them to inspect small patches and cracks on the tower without exposing workers under extremely dangerous conditions.
Emley Moor Tower, owned by the British telecommunication company – Arqiva and officially named as Arqiva Tower, is the tallest freestanding structure in the United Kingdom. The transmission tower currently broadcasts over 10,000 square kilometers, including six digital television multiplexes, three digital radio ensembles and two independent local radio stations Capital Yorkshire and Heart Yorkshire. The need of inspection and maintenance of the tower can be stressed that the repair work in 2006 were estimated to have influenced around 5,000,000 homes!
Traditional Method VS. Drone Mapping Inspection
The application of drone mapping in this project was a truly success! For such tall structures, laser scanning is nearly impossible. A traditional way to inspect the 1,084-feet (330-meter) height tower is to take high resolution ground photographs or to have people reach the top by elevator and descend with ropes and harness, taking high-resolution pictures of problematic areas on the tower structure and recording the rough height and position along with descriptive notes.
In June, 2016, Arqiva requested the British aerial survey providing company, RSK Orbital, to complete an external inspection of the tower. RSK Orbital was already an user of Pix4D software for nearly a year, and they contacted Pix4D immediately for advises, making sure the project will be successfully and efficiently done. The results were impressive and make the survey work much more easily and accessible for the client.
Disadvantage of previous inspection method:
– Problematic spots not noticed
– Time consuming
– Safety issue involved for personal due to working at height
Despite the difficulty and time consumed for getting a permission, the workers are working in a dangerous environment when descending from the tower. On such a large tower it is difficult to ensure 100% coverage but neglecting small damage at early phases could dramatically raise the repairing costs by several times or even make the structure not repairable.
For workers on site, the use of rope access techniques can present real risks and even minor mistakes could result in major incidents. By using drone mapping technology, it shortens the time and cost of inspection without putting the workers exposed in dangerous condition. Even more, the results are of higher quality and can be preserved forever. In our project, for example, the processed results contain all information and details in 3D. In the Pix4D software interface, we could simply click on any patch we found on the tower and immediately know its position in accurate 3D coordinates and all the original high-resolution images contain that patch!
Biggest Challenge for the Project
When collecting data using the DJI Inspire 1 the most difficult situations we faced were strong wind and the interference from the radio waves. We had carefully planned the work and accounted for all conceivable hazards within our risk assessments and method statements.
As the tower itself was well over the 400ft ceiling applied to most ‘Drone’ operations in the UK RSK Orbital had to put forward a safety case to the Civil Aviation Authority which was approved and allowed a flights to the top of the 1084ft tower.