Case Reports

Designer's duty to verify design assumptions

Initial design almost always proceeds on the basis of assumptions. In Ove Arup & Partners International Ltd and Ove Arup & Partners Hong Kong -v- Mirant Asia Pacific Construction (Hong Kong) Ltd [2005] EWCA Civ 1585, the Court of Appeal found that the designer's duty to design with due care and skill includes a duty to verify any design assumptions adopted by it.  A designer may not be required to obtain the information personally however they must ensure that someone obtains the information necessary to verify the design assumption and, in particular, ensure that the client is informed of the need to obtain it. The court found that, unless the designer gives the client an explicit warning and disclaimer, it is not sufficient to leave it to the client to obtain and evaluate the information. There was little guidance from the Court on the sort of activities are required to discharge this obligation. However, it did note that for certain contracts a surface examination of ground conditions would be sufficient to discharge its duty to verify, but that in this case and the contact in issue, that this was insufficient. What is clear is that what steps a designer must undertake to fulfill its duty to verify will depend on the terms of the particular contract and circumstances of the case.

The Court also found that confirmation that the design intent is fulfilled is different from verification of the design assumptions.

Synopsis of Case:

Ove Arup were engaged CEPA Slipform Power Systems Ltd (later changing its name to “Mirant”) to design the foundations of a boiler house for a power station in the Philippines. Ove Arup were to develop a concept design through its Hong Kong office with preliminary and detailed design to be performed in the United Kingdom.

Initial ground investigations, carried out by Ove Arup experts, discovered faults in the underlying rock formation. A report on the initial ground investigations noted that variable and often low strength rock, even at considerable depth, may cause foundation problems for heavily loaded structures. Work on the design commenced on the basis of the rock having an assumed maximum bearing capacity of 3MPa (megapascals). In the initial hearing the Judge found that this was a “preliminary assumption which was to be subject to detailed verification”. Ove Arup commenced work on the detailed design before confirmation of the assumed maximum bearing capacity of the rock was obtained.

Subsequent to the preliminary design, the parties entered into a ground investigation agreement pursuant to which Over Arup were to supervise further ground investigation work and, on request, inspect and approve ground condition foundations. The Court found that the subsequent investigations were not the systematic investigations which Over Arup had earlier identified as being required to verify the design assumption and were insufficient.

The foundations of the boiled house, built in 1996, failed in 1997.  Mirant commenced proceedings against Over Arup for breach of contract.