Innovative Concrete Machinery on Mersey Bridge

bridge

An Anglo-Spanish-Korean contracting team is using some innovative formwork machinery to build the Mersey Gateway bridge in northwest England.

The €770m project will provide a new road crossing over the River Mersey estuary between the towns of Runcorn and Widnes. The construction consortium building the bridge is called Merseylink. Its members are Kier (UK), FCC Construcción (Spain) and Samsung C&T (Korea).

The new bridge (shown in CGI above) will carry three lanes of traffic in each direction. Including the approach viaducts on each side, it will be 2,130 metres long with a river span of 1,000 metres. Completion is scheduled for the fourth quarter of 2017.

Construction of the bridge and its approach viaducts is seeing the use of some interesting formwork equipment that has been developed especially for this project.

The elevated approach viaducts are being built out of reinforced concrete using a specially-built movable scaffold system (MSS). It is 157 metres long, 22 metres wide and weighs 1500 tonnes, making it the longest machine of this type in Europe It can cast spans of up to 70 metres.

It is used for casting the curved approach spans on each – first one side, then dismantled and transported to the other side to do the same job there.

The project team has called this machine Trinity. It began work on 21st January 2016 with a concrete pour for the first deck section of the northern approach viaduct (pictured below). Each pour typically takes 24-hours and 160 truckloads of concrete to fill the 1,170 cubic metre formwork mould.

Trinity

The MSS only builds the central part of the road. The outer lanes are built by a wing traveller machine (pictured below). This is 48 metres wide, 20 metres tall and weighs 280 tonnes.  Like the MSS, it provides moveable formwork for concrete pours. It is fixed onto two railway tracks that sit on top of the deck section previously cast by the MSS.

Concrete is poured into both sides of the machine at the same time, enabling contractors to cast 12-metre sections of the outer deck on each side of the viaduct. Once the concrete is set, hydraulic jacks push the machine forward to the next position.
wing traveller

Two wing traveller machines will be used on the project – one for each of the approach viaducts. There are 62 concrete pours needed to create the outer deck of the north approach viaduct and 47 for the outer deck of the south approach viaduct. Each pour will consist of around 80 cubic metres of concrete (40 on each side).

The main bridge itself has an unusual design. It is cable stayed, which is not unusual, but of the three pylons supporting the cables, the middle one is the shortest rather than the tallest. The outer ones are 110 and 125 metres high; the central pylon is just 80 metres.

The pylons are made from concrete using specialist auto-climbing system formwork. After each section of pylon is constructed, the formwork climbs up to create the next section.

The deck of the main bridge is being built using form travellers that act as movable concrete moulds like the MSS used on the approach viaducts.

The photo below shows both the form traveller that provides formwork for the main deck and also the pylon formwork system.

form-traveller

Steve Rhine

About Steve Rhine

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