Both the traditional forms of contract SBC/Q2016 and MWD2016 are quality-driven contracts. That is, they envisage that separate consultant designers will be appointed to produce detailed designs with a contractor carrying out the work strictly in accordance with the designs. The designers not only produce the detailed design but also perform supervisory functions under the contract, including authorising interim and final payment, practical completion of the work and final certification that the works are complete as intended. It is largely through payment and completion certificates that the quality of work is controlled.