Whalley viaduct built in 1846 stretches across the river Calder. The viaduct is a magnificent structure, consisting of 49 brick arches, 620m long and 21.3m high. Locally the area is known the Whalley Arches.
Traditionally, the surveying and inspection of these structures would be undertaken manually, with measurements and repetitive paper-based data entry. The traditional method is both time consuming and expensive; requiring extensive scaffolding.
To eliminate the human errors attached to traditional surveying, and to save on time, we employ terrestrial 3D laser scanning techniques to capture buildings and structure data. Combined with photography of the structure, the laser scan data assists in assessments, helping with the prioritisation of maintenance issues,which may or maynot be required.
Our team travelled to Whalley Arches late in the evening, our job was to scan the top railway section at midnight, the best time to work when scanning railways – whilst trains were stopped. However, due to strong wind gusts and torrential rain, the night time scan was cancelled much to our dismay. Undeterred, the next morning, clear skies and a mild breeze greeted us as we set off with a RIEGL scanner, two drones and camera team to capture the arches.
Several areas under the arches required cleaning out of saplings, brambles and general discarded waste. These were cleared by the ever helpful team from Network Rail, armed with Chainsaws, and industrial hedge trimmers. As soon as these obstacles were cleared, giving us line of sight for the scanner and operator and easier access to the grounds, our job commenced.
Each arch was scanned with terrestrial lidar, which made for some interesting scrambling up embankments and into residents gardens to ensure a clear view of the arches for the scanner.
Thanks to all the residents who allowed us into their property, who were all very kind and welcoming.
A total of 187 scan positions, combined with 3,000 high resolution photographs gave us a highly detailed accurate comprehensive analysis of the complete structure.