I am replying to Mr Flint's letter (NCE 30 September) on the Millennium Wheel's lift problems. I personally supervised the client's investigation and the subsequent testing and review of the contractor's new connection design. The facts are as follows:
The strand bundles did not snap.
The wedges and anchor heads did not fail in any way.
Pre-tensioning was carried out.
The five cables that became detached remained connected at the spindle end.
The collapse sequence occurred at the connection to the rim.
The collapse sequence was largely as a result of misalignments and the inability of the head of the connection to rotate.
The collapse of the connection was not caused by wedge failure. Wedge failures do happen in such lift systems and I began the investigation with that as one of the potential causes. Wedge failure was positively ruled out on inspection of the cable ends. The wedge collars were present and intact.
Neil Thompson, Design Manager, Mace Limited, British Airways London Eye, Site Office, 20 Belvedere Road, London, SE1 7FW