Project Overview
The Çanakkale 1915 Bridge connects the Turkish towns of Lapseki and Gelibolu (Gallipoli) and represents a major achievement in international bridge engineering. The bridge is supported by two enormous reinforced concrete caissons, each weighing approximately 66,000 tonnes and measuring 74 × 83 metres with a height of 20 metres. These foundations were installed on the seabed at a depth of 45 metres.
During an impressive 72-hour installation operation, Strukton Immersion Projects (SImP) successfully lowered the caissons into position with an extraordinary positioning accuracy of just 10 millimetres.
Challenge: Controlled Installation at Great Water Depth
Installing structures of this size at a depth of 45 metres presented significant engineering challenges. The combination of the caissons’ enormous dimensions, extremely tight installation tolerances and demanding offshore conditions required innovative engineering solutions and meticulous planning.
Our Approach and Scope of Work
1. Modelling the Float-Out and Tow Operation
MH Poly developed a dynamic engineering model for the float-out and winching operation of the caissons. The scope included:
- Calculating winch loads
- Determining the optimal winch positions
- Optimising transport and towing scenarios
This ensured a safe, controlled and efficient transport operation from the construction dock to the installation site.
2. Design of the Underwater Positioning System
Working closely with Strukton Immersion Projects, MH Poly designed an innovative underwater guidance and positioning system that enabled the caissons to be installed with exceptional accuracy.
The system consisted of:
- Four seabed guidance structures
- Four hydraulic jacks mounted on the caissons
- Sliding surfaces with articulated hinge mechanisms
- D-fenders for impact energy absorption
This system allowed the caissons to be actively adjusted while suspended just above the seabed, ensuring precise alignment before final placement.
3. Engineering of Installation and Lifting Frames
To facilitate the accurate installation of the seabed guidance structures, MH Poly designed:
- A heading frame for precise alignment
- A multifunctional lifting frame for installation operations
These purpose-built tools enabled installation within extremely tight tolerances, even at significant water depth.
Result
Thanks to the close collaboration between MH Poly and Strukton Immersion Projects, both caissons were successfully installed with a final deviation of only 1 centimetre from the target position.
Why This Project Is Unique
- Foundations for the world’s longest suspension bridge main span
- Two reinforced concrete caissons weighing 66,000 tonnes each
- Installation at a water depth of 45 metres
- Positioning accuracy of up to 10 mm
- Innovative underwater guidance and positioning system
