This revolutionary approach to the manufacture was devised by Hartlepool Steel Fabrications, which won the contract to build the Angel of the North. They worked closely with consulting engineers Ove Arup & Partners and Gateshead Council to make the design of the Angel a reality.
Hartlepool Steel is a family-owned firm which recently finished renovating Middlesbrough's Transporter Bridge. It has also worked on North Sea oil rigs and in the Teesside chemical industry.
The original body castings of the Angel by the sculptor, Antony Gormley OBE, were scanned by the Geomatics Department at Newcastle University and the precise co-ordinates plotted to create an electronic, 3D Virtual Reality Angel.
This data was converted into a three-dimensional CAD model by Grafton Software so that the computerised profiling machines used by Teesside Profilers were able to cut the main body into ribs following the exact curves of the artist's original castings. The ribs were then supplied to Hartlepool Steel for construction.
The foundations for the Angel are almost as impressive as the artwork itself.
One hundred and fifty tonnes of concrete were poured to form piles to root the sculpture into solid rock 20 metres below.
Windloads on the wing boxes were transmitted along the ribs, down the body and into the foundations, enabling it to withstand winds of more than 100 miles per hour.
A Cumbrian firm won the contract to install the foundations, Thomas Armstrong (Construction) Ltd, whose North East Regional Office in Catterick, North Yorkshire, oversaw the work.