However, lack of mobilisation payments linked to milestones and the complexity of bespoke schemes led to significant costs and risk carried by the contractor.
Fodd bynnag, mae diffyg taliadau paratoi sy'n gysylltiedig â cherrig milltir a chymhlethdod cynlluniau pwrpasol yn arwain at gostau a risg sylweddol i'r contractwr.