New Queensferry crossing takes another step towards completion

THE gap is closing on construction of the new Queensferry crossing.

Saturday, 19th March 2016, 11:54 am
Updated Saturday, 19th March 2016, 11:54 am
Keith Brown pictured with Jared Carlson and Jennifer Bullingham, engineers who have worked on the launch of the Queensferry Crossing's north approach viaduct, successfully launched earlier this month. Picture: Transport Scotland

Engineers on the project have completed the complex process of pushing the massive viaduct out across the bridge’s distinctive V-shaped piers on the north side of the Forth – and there is now a distance of just 64 metres, about the width of a football pitch, before it is connected up.

Infrastructure Secretary Keith Brown visited the crossing to view the latest progress.

He said: “If any further evidence is required to demonstrate large-scale, world-class engineering, look no further than the latest progress on the Queensferry Crossing.

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“Having been fortunate enough to see construction close up and to speak with some of those directly involved in the construction of this structure, I have a true sense of the scale of the work being achieved every day on the project. It really is remarkable.”

He said completing the north viaduct launch was another significant technical milestone for the project.

“Pushing such a huge structure in such a controlled manner, working to a tolerance of a few millimetres, requires expert planning and execution. It is clear that highly skilled and experienced engineers are bringing their knowledge to the project, while others are taking the opportunity to gather their experience.”

Unlike the south viaduct, which was constructed in sections, the north viaduct was fully assembled on site and pushed out over static temporary supports as a single operation.

As well as being pushed out, the viaduct was rotated and pivoted upwards, making sure that it rolled over the top of the piers. Around 48 miles of cables were used to complete the launch – enough to stretch from Rosyth to Glasgow when laid end to end.

Michael Martin, project director for the consortium building the new bridge, Forth Crossing Bridge Constructors, said: “The launch of the north approach viaduct into its final position has been one of the most technically challenging operations of its type ever performed.

“A massive total of 6300 tonnes of steel and concrete was launched out 230 metres – in itself a significant feat of engineering.

“But what makes this operation really special is the fact that we had to slide the trailing edge of the moving structure down two ramp walls in order to raise the front edge by two metres. This allowed us to pivot the entire structure over the top of one of the two support piers as it moved forwards, resulting in the viaduct structure being at the correct geometry to match the emerging deck coming from the north tower.

“This operation was extremely technically challenging. It required the ingenuity of some of the best engineers in the world, to design and build the structure and devise the method of safely and successfully launching it out into position. This is the kind of work being delivered on a daily basis right across this amazing project.”

The £1.35 billion crossing is due to open to traffic in December this year.