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Muir Wood: lessons of the HEX verdict

The trial concerning the tunnel collapse at Heathrow in October 1994 has ended with a guilty verdict in the indictment by HSE against the two defendents, Balfour Beatty and Geoconsult. It is now possible, in consequence, to draw attention to lessons from this incident of wider public interest.

There has been wide agreement in the trial that a material factor to the collapse was the nature of the system of project and contract management, with all engineering of the NATM process - including quality control - devolved to the contractor with self certification as part of a competitive contract. Powers for controlling the engineering by the Heathrow Express (HEX) management team, which included Mott MacDonald (who advised against such an inhibition) was virtually confined to a remote procedure of audit. Informal support with monitoring, of which NATM is an example, depends on a highly interactive relationship between design and construction, recognising that the design, which includes design of all aspects of the features of construction, should dominate the process.

It is now claimed that the HEX project was based on the New Engineering Contract which bears the imprimatur of the ICE. I was one of those invited to comment on a draft of the NEC and expressed astonishment that the concept of the Engineer (of the ICE and FIDIC Conditions - highly successful where the Engineers was appointed on merit and without constraint by lawyers) was to be abandoned without any other mechanism for providing the engineering continuity essential for a project in which design continued into the phase of construction. No attempt was made to remove this defect from the published document. For this reason, the NEC provides no adequate basis for tunnelling, where continuity of design is an imperative, nor for many other forms of construction. There are many ways of providing this continuity but the NEC, which lacks evidence of understanding the vital features of engineering, does not even address the problem. The issue was not addressed by the ICE Guide Sprayed concrete linings (NATM) for tunnels in soft ground (1996) which states: 'Provided that an appropriate specification is included in the contract documentation then all standard forms of contact can be used for the procurement of SCL system tunnels.' This statement is not true where the Conditions of Contract impose inappropriate allocation of responsibility and, through the pricing mechanism, effectively prevent co-operation between design and construction to optimise a project and resolve problems.

It should not have required a costly disaster to learn the lesson that a contract should be built around the engineering desiderata for success. I believe the Institution should now issue a 'health warning' in relation to the use of the NEC and should set to work without delay in producing a successor as a worthy basis for good engineering for the next century.

It is particularly odd that BAA should have been involved for HEX, prior to the collapse, in practices which seem so remote from the enlightened attitudes expressed by Sir John Egan and demonstrated, for example, in the planning for Terminal 5. When work was resumed for HEX after the collapse, enlightenment prevailed here too, with a successful recovery of a totally unnecessary and costly incident.

Sir Alan Muir Wood (F), Franklands, Bere Court Road, Pangbourne Berks RG8 8JY

(see News page 3)

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