The Project Brief is normally accompanied by a document called the Principal's Requirements. This document sets out in some detail the characteristics of the service that is required.
There is a temptation for the Principal's Requirements to spell out minimum construction standards. This should be avoided as far as possible in order to maximise the contractor's scope to innovate and find cost-effective solutions. See comments in chapter 4 above. Concerns about the future reliability of the service should be addressed through appropriate payment mechanism incentives. See section on payment mechanisms below.
Bidders sometimes offer minimum construction standards. There is a temptation to write these into the contract in order to be able to hold the bidder to them, especially where the bidder was preferred over others because of the higher construction standard. Again, this should generally be resisted in favour of holding the bidder to a particular service standard. An alternative is to write the bidder proposals into the contract but with a lower level of precedence than the output specification. The contractor can then be given flexibility to change its proposals but only to the extent that quality is not impaired and the output specification is still met.