An additional benefit that PPPs provide over more traditional contracting models is the benefit of contractual certainty in relation to the entire transaction at the time government enters into the first major contract for the project. Alternative delivery models often involve government separately contracting different parts of the project progressively. The designer is contracted ahead of the construction contractor, and if the works are spread across multiple construction contracts, most will be engaged before the total construction price is finally contracted. The operation and/or maintenance contractors are usually only engaged late in the construction process. Circumstances often change between the time the government enters into the first major contract for a project, and the time it enters into the last one, many years later. There will often be a change of Minister over this period, and perhaps even a change of government. The scope of the project often grows, and the final cost ends of higher than was anticipated at the time the initial major contract was signed. Having started the project, government needs to finish it. However, had government known the full cost at the time it signed the first contract, it may not have proceeded with the project in its then form or at all. A PPP avoids this situation by requiring all necessary contracts to design, build, operate and maintain the project to be signed before the government becomes bound by the PPP contract, thereby providing government with much more certainty at the time it contractually commits to the project.