Case study //

60km-corridor-fly-through-and-topographic-survey

Category: Construction Monitoring

Client: J Murphy & Sons Ltd (JMS)
Norfolk Offshore Wind Zone (NOWZ) – Onshore Works

Date: Regularly since October 2023. Monthly mapping ongoing.

Summary: Monthly detailed aerial mapping for construction monitoring of the 60km cable corridor and mobilisation areas for the Norfolk Offshore Wind Zone (NOWZ) projects: Vanguard West, Vanguard East and Boreas.

Monitoring the potentially rapid progress of work on a 60km long construction site can be highly challenging. As work fronts move out from mobilisation areas and road crossing points are established, a fast and unobtrusive method of site monitoring is needed to keep up with rapidly changing site conditions without impeding progress on the ground. Capturing detailed ‘blanket coverage’ imagery of every square metre of the site from ground level would be extremely time consuming and involve challenging access across mainly agricultural land. An aerial perspective can reveal features and potential emerging issues that would be hard or impossible to spot at ground level.

Following on from its video fly-through and LiDAR survey Early Works Project work, HexCam was engaged by J Murphy and Sons Ltd in autumn 2023 to start regular (monthly) site mapping flights as part of the main NOWZ Construction Works Project. Initially starting with a 20km section between Necton and the River Wensum, it’s hoped that similar regular site aerial mapping will be utilised for the remaining 40km as work progresses eastwards towards Happisburgh.

HexCam’s familiarity with the corridor route and the stakeholder engagement process allowed us to quickly start planning the best locations for Take-Off and Landing Sites (TOLS). Our CAA ‘Operating Safety Case’ (OSC), incorporating Extended Visual Line Of Sight (EVLOS) operations, allowed us to significantly extend our flight distances and to design the most efficient flight routes for good quality high resolution image capture. We worked closely with JMS and RSK Consents Solutions to ensure that landowners were updated on our flight plans and ground crew access requirements at all times.

Our DJI M300 RTK survey drone, carrying DJI’s ‘P1’ high resolution full-frame camera, allows us to fly higher and faster without any loss of detail in images captured.

Imagery is rapidly processed and presented using Drone Deploy to provide JMS with a highly detailed and, importantly, up-to-date map of the construction site. As well as providing the project team with detailed 2D mapping layered over key project drawings, original geolocated high resolution (1.5cm per pixel) images are instantly available for closer inspection of works. 3D modelling is also provided allowing cut and fill volumetrics to be quickly calculated and the site to be viewed from any angle.

Points of interest can be annotated on the map and shared between team members providing a valuable collaborative tool for monitoring and quantifying site progress and for managing land owner relationships.

Mapping flights for the first 20km route are completed in just under 1 day, with police, landowners and other air users kept constantly updated on our flight locations and rate of progress.