TUNNEL MONITORING instruments predicted a cave-in at Heathrow Express weeks before the actual collapse but the consultant responsible failed to act, a court heard this week
'Geoconsult was the watchdog that failed to bark,' prosecuting counsel Hugh Carlisle QC told the jury as he opened the Health & Safety Executive's case against Austrian tunnelling consultant Geoconsult and contractor Balfour Beatty in the Heathrow Express Rail Link tunnel collapse trial on Monday.
The trial started amid confusion as Geoconsult failed to turn up to contest two charges under the Health & Safety at Work Act of endangering its employees and others. Contractor Balfour Beatty pleaded guilty to virtually identical offences.
Charges were brought by the HSE after the collapse of New Austrian Tunnelling Method tunnels in October 1994 at the Central Terminal Area of Heathrow Airport during construction of the £440M Heathrow Express Rail Link. No one was killed in the accident.
Opening the trial's first full day, the judge Mr Justice Cresswell read an agreed statement to explain Geoconsult's absence. He told the jury that the consultant had withdrawn instructions to its lawyers and that the trial would proceed without representation.
Last week Geoconsult had warned that the likely cost of defending itself throughout the trial could give it serious financial problems. It added confusion to a trial which was due to start last week but had been dogged by prolonged legal arguments.
The move left Carlisle to outline the HSE's case against Geoconsult unchallenged. He explained that Geoconsult had a £1M contract for the design and technical supervision of construction on Balfour Beatty's design and build contract to build three NATM tunnels under Heathrow Airport's Central Terminal Area.
Carlisle said tunnelling problems began in August 1994 when higher than expected settlement of Cambourne House alongside the main shaft was recorded. Compensation grouting to reinforce the ground and jack up the building was carried out.
But, he said, this increased loadings on the tunnel which started to deform. Carlisle argued that remedial action to repair cracks on the tunnel invert were insufficient and that the situation was made worse when simultaneous tunnelling on all three tunnels was started to make up lost time.
The desire for progress 'overcame their heads', said Carlisle. 'A major disaster was only avoided because of luck, not judgement,' he claimed, adding: 'This must be rated as one of the worst civil engineering failures in recent years.
'The mind boggles at what the consequences might have been if the tunnel had continued to unzip back up to the Piccadilly Line,' said Carlisle.
Towards the end of September movements in the concourse tunnel began to accelerate, he told the jury. 'Geoconsult should have been aware of the problems but did nothing.'
Quoting the conclusions of a report by expert witness former ICE President Sir Alan Muir Wood, Carlisle said that impending disaster was clear over two weeks before the collapse but no indication was given. This was Geoconsult's responsibility and it got it wrong, he pointed out.
Carlisle read out site memos and diary entries which showed that workers were unaware a collapse was imminent. One notice said that permission had been given the day before to open up the tunnel to full face excavation.
Miners evacuated from the tunnel on the night of the collapse told the jury how shotcrete was seen spalling from movements in the tunnel walls and floors as they worked just hours before the collapse.
Carlisle explained that once the prosecution had proved that there was an exposure to risk the burden of proof was with the defence to show it had done all that was reasonably practicable to reduce that risk. 'The fact that they are not here is significant,' he said. The lack of defence meant the witnesses could not be cross examined.
The trial continues.