'You could see movements in the invert where repairs were being done,' Balfour Beatty miner Nigel McBirnie told the court. He was working on repairs to the defective tunnel invert joint on the night of the collapse. 'I saw pieces of the lining falling. That was enough for me to get out.'
McBirnie's brother Robert was also in the tunnels on the night of the collapse. 'We were repairing hairline cracks. We would put in mesh and by the time it was ready for sprayed concrete the mesh had distorted,' he told the court. 'It was moving in front of my eyes.'
'Movements in the invert were getting worse through the shift,' fellow miner Andrew Merch told the court. 'We would put the mesh in, spray concrete it, then the mesh would pop back up through the sprayed concrete within minutes.'
Balfour Beatty engineer Simon Welsh, who was seconded to act as a NATM monitoring engineer for Geoconsult was able to draw sketches of the cracking in the tunnels just before the collapse. These formed an important part of Geoconsult's defence (page 5).
'The crown of the downline tunnel was moving down relative to the invert in such a way that the crown appeared to be moving outside the lining,' explained Welsh.
'While I was working I could hear cracking noises in the tunnel,' said miner Patrick McKenna in a statement read out to the court. 'I felt uneasy but carried on. The middle of the invert started to buckle up so there was a hump.'
Brian Staley was the Balfour Beatty foreman responsible for the tunnelling work and had gone home after the end of the day shift. He was called to site just after midnight about an hour before the collapse.
'We were all shaken up by what we saw,' he said. 'The downline tunnel was cracked and mesh was exposed. Sprayed concrete was spalling off the side of the concourse tunnel. Pieces were falling so I made the decision that it was time to go,' he said. 'As soon as I saw the cracks in the tunnels I knew it was collapsing. It was too late to save anything.'
The miners told the court that the everybody was evacuated out of the tunnel and across a hard standing area to the site canteen. When it was realised that the ground under the canteen was also collapsing everybody was evacuated off site.
Merch added: 'After a few minutes we were told to evacuate the canteen. The ground started to suck down.'
'The car park was formed in a series of concrete planks,' NATM engineer Simon Welsh told the jury. 'There were no cracks but the edges of the planks showed signs of spalling. After a time you could feel the actual slabs falling an inch or two as the ground below fell.'