Integrated Solutions – Tunnel construction and immersion
Challenge
Our client, Ballast Nedam, required the safe movement and precise positioning of ten concrete tunnel elements, each weighing approximately 47,000 tonnes, from a flooded precast construction dock to their final locations in the Khor Al-Zubair channel for controlled immersion. The tunnel will enable road traffic to cross the channel as part of a newly constructed route linking Al Faw Port, at Iraq’s southernmost tip, with Baghdad and onward to Turkey.
This operation involved highly complex heavy-lift logistics using floating pontoons and anchor systems in strong river currents, while also operating under restricted marine access conditions, as installation activities had to be carefully planned to minimise disruption on active shipping lanes.
Solution
To address uncertainties in the river conditions and achieve precision manoeuvring of the tunnel elements, Valeport 106 current meters and data logging equipment was installed on the winch pontoons, enabling live current monitoring. Current speed and direction were continuously monitored, providing reliable data capture which was used to improve the efficiency of each tunnel installation over an eight-month period.
Prior to project execution commencement – and in close collaboration with our client, we identified an issue with a winch concrete anchor point. To mitigate against major structural modifications and project delay, we engineered a practical solution by introducing an additional swivel head fairlead, to overcome the issue, avoiding significant cost and operational impact for the client.
Ashtead Technology’s project approach places considerable importance on execution planning and assurance to give our client full confidence in operational execution. On this project, we undertook a comprehensive sea fastening analysis and deck reaction assessment to assure the installed winches were securely fastened across load case scenarios.
Following the execution planning and assurance phase of the project, Ashtead Technology mobilised, installed, commissioned and operated specialist winch systems and associated equipment across two project phases. This included a spooling winch package and 18 hydraulic winch systems, ranging from 8Te to 120Te, complete with hydraulic power units and running line monitors for transmitting realtime winch load data to the immersion command centre.
Phase one involved the spooling of the clients 52mm wire ropes onto 14 of the hydraulic winches using our dedicated 100Te spooling winch and high tension drum.
Phase two covered winch commissioning, warping, and tunnel element installation activities, with our winch systems providing transportation and controlled positioning of each tunnel element to its immersion location and holding each element in position during progressive immersion.
In addition to equipment supply, we provided field personnel for the duration of the eight-month long period. Our personnel functioned as an extension to our client’s field team with the Ashtead Technology Senior Project Manager appointed as Warping Commander by the client, to lead the controlled movement of the tunnel elements from the storage yard to their exact submersion position.
By implementing an experienced, command-led approach, we reinforced overall safety, precision, and efficiency during successful completion across all phases of the project.
Results and impact
- All ten tunnel elements were safely and successfully; floated from the precast dock, winched to temporary mooring locations for fit-out, transported to their immersion locations and held steady on location whilst lowered accurately onto seabed supports and connected sequentially across the river.
- Solutions-led approach to identifying and implementing continuous current monitoring, enabling safer operations and improved planning accuracy leading to installation efficiencies.
- These activities were underpinned by our comprehensive equipment portfolio, supporting both topside operations and survey requirements.
- Improved communication and safety alignment ensured operations met international safety standards despite challenging local conditions.
- The project was delivered with safe execution within a live shipping environment with minimal closures.
To learn more contact our Mechanical Solutions team.