The “Trinity” movable scaffolding system (MSS), specially designed for the construction of the curved viaduct leading to the main bridge, began yesterday to build the first section of the north viaduct approach deck from the Widnes side of the River Mersey.

“Trinity”, which measures 157 metres by 22 metres and weighs 1,700 tons, will remain on the project for the next 14 months. Starting on the 21st January, she was fed around 1,170 cubic metres of ready mixed concrete over a period 34 hours.

The movable scaffolding system (MSS) contains the formwork for building the central deck of the north and south approach viaducts, which will be built in sections or spans about 70 metres long.

Several weeks will be needed to build each of the 19 spans using this construction system, so that operations are due to be completed in Spring 2017.

The process involves anchoring the movable scaffolding system between two pillars of the viaduct in order to pour concrete into the structure that acts as formwork to create the deck.  After completing the span, the equipment advances by means of a hydraulic system to the point where it is required to build the following section.
Given the width of the deck, this construction process has to be carried out in two separate phases, firstly by running the MSS, while in a second phase, the cantilever wings are added to complete the viaduct .

You can see how the construction process is developing through the following link: https://youtu.be/5J1z7KcsvCs .