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When designers are caught between a rock and a hard place

legal matters

'This case is worthy of consideration as it shows that a claim for over-design is a possibility.'

Most construction professionals are all too well aware of the possibility of litigation and consequently err on the side of caution. Assume, for example,that you are given a design brief for a substantial public building, and your client stipulates not a 40-year, but a 400-year, design life. Conscious of such an onerous and ambitious requirement, an engineer or architect might well adopt a belt- and-braces approach to design. But does over-provision ensure protection from a negligence claim?

The answer, it seems, is perhaps not. Judging by an early piece of legal fall-out from the Jubilee Line Extension, the designer might find himself caught between the proverbial rock and the hard place.

Kenchington Ford, which provided civil-engineering and architectural design for the station at Canning Town, had been faced with just such a brief. After its work was complete, it was sued by London Underground, one aspect of the claim being that the concourse slab was over-designed and that it could have been thinner and cheaper.

There was no suggestion that the slab as constructed was not reliable and successful, only that it had cost more than it needed to.

Happily for the engineer, the judge found that it had not been negligent in respect of this part of London Underground's claim. But the case is worthy of consideration as it shows that a claim for over-design is a possibility.

The judgment sets out that, to succeed, London Underground would have had to prove two things. First, to meet the test that applies in all professional negligence matters, namely that there was a responsible body of competent consultant engineers which, at the time the design work was done, could have adopted a substantially different design approach. Secondly, and more unusually, it had to try to prove that there was an acceptable alternative scheme, such an alternative being put forward by its expert witness.

The factors which influenced the judge in his decision are informative. He accepted that the design life, which was 120 years for superstructures and 400 years for substructures, dictated 'an extremely conservative approach', especially given that the work was being carried out by a public body on a prestigious structure. London Underground was technically able, and as a result the judge found it possible to conclude that it was sufficiently knowledgeable to know what it needed and what it was that it wanted the engineer to do.

In addition, the judge found that the

client had emphasised, throughout the design process, the importance of both the time that construction would take and how easy it would be. London Underground's alternative scheme, which it argued for in court, would have required, by its own account, 57 more piles than the slab as it was constructed.

As a result the judge was not persuaded that London Underground would, had it been presented with the alternative at the time, have accepted it.

Finally, and somewhat removed from the facts of the case, it is interesting to reflect on and compare the position of a quantity surveyor if faced with a similar dilemma. When confronted by uncertainty, he does the equivalent of over-designing by writing in more money.

There is, of course, the possibility that if the price is pushed too high the contract will not go ahead. But, assuming that it does, and he has allowed a sufficient margin to accommodate the unknowns, unlike the over-designing engineer or architect, he is not vulnerable. The client suffers no loss. And if the risks do not materialise, he is a hero, the job being delivered under budget.

A long way from the tightrope walked by the designer.

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