Mersey Gateway Project moves forward with huge bridge-building machines deployed

Huge bridge-building machines have been deployed in the Mersey estuary as work gets underway on the Mersey Gateway Project’s main bridge deck, marking a new milestone for the multi-million pound development.

Two of the six form traveller machines constructing the river crossing in Halton are now operational, moving apart for the first time at the south pylon this week to make way for the construction of the 1,000m-long reinforced concrete bridge deck across the Mersey.

The machines, each of which weighs 270 tonnes, act as movable concrete moulds during the build process.

The form travellers were put together at the south pylon earlier this year, then lifted to their starting position around 25m above the riverbed. Construction teams cast a rectangular platform called a pier table around the bridge pylon, enabling them to start work on the main bridge deck.

Kyuyoung Choi, operations manager for the main crossing at Merseylink, the consortium behind the project, said of the building process: “Each segment of the bridge deck is made in the same way.

“Reinforced steel is placed into the mould and we then pour around 130 cubic metres of concrete inside to create each segment.”

He continued: “From the third segment onwards, we install the connection boxes, which are called ‘delta frames’, for the steel stay cables, which are then attached to the upper pylon. The form travellers, which are powered by a hydraulic system, then move forward on a set of rails to the next position and the process is repeated.

“The deck segments are cast simultaneously, which allows the bridge deck to ‘grow’ from either side of the pylons until it meets the connecting bridge deck and the structure is complete.”

In total, three pairs of form travellers will be used to build the bridge deck, with each pair operating as a single unit. The machines will be launched from the north pylon later in September and from the central pylon next month.

Work on the deck is due to finish in Summer 2017, with the bridge opening to the public in Autumn 2017.

The Leader of Halton Borough Council, Cllr Rob Polhill, commented: “The three bridge pylons under construction are already giving us a glimpse of a much anticipated view of what will be become a landmark structure in our borough and indeed across the North West.

“The launch of the form traveller marks the next, thrilling stage of the project and I’m excited to see the bridge deck emerging across the river.”

The form traveller machines were specifically designed and built for the Mersey Gateway Project. Once the complete, the machines will be taken apart and recycled.