The piling and civil works of the London City Airport expansion are carried out in a basin formed by the Thames River and the King George V dock. Working in this environment presents a unique constraint for the overall safety of the airport, its operations, the general public and the nearby residents, particular when using floating equipment and carrying out piling works.
Because this area, like large parts of East London, suffered severe bombardments during the blitz of the second world war, there is a high risk of encountering Unexploded Ordnances (UXOs) in the dock bed, therefore using floating equipment poses particular challenges for mooring, as standard anchors or dead men cannot be used and spud legs are also discarded.
While the are two dock walls, as the piling barges move away from them, the distance is too long to use anchors installed in the dock walls. Besides, the mooring cables would interfere with the construction of the new deck.
Based on the conditions mentioned above, BAM’s Plant Engineering department developed, since the tender phase, a unique solution based on mooring barges that can moor on the dock walls or on the already installed piles, and then serve as the berthing line for the piling barges. The mooring barges are equipped with piles guides on both sides, so that the starboard side is used for clamping onto the already installed piles and the port side ones are used for the installation of the new piles.
The mooring barges are a purpose-built piece of equipment made of modular pontoons and are fitted with six piling guides on the port side.