PPPs are whole-of-life contracts which combine a 'fixed price / no progress payments' contract with a long-term service delivery contract. The contractor is paid by way of service payments over the life of the contract. At the end of the contract, ownership of the asset usually reverts to the government, although this is not an essential feature.
Since service payments are pre-specified in the contract, cost overruns from the client's (ie, government's) point of view are therefore unlikely.
Because the contractor bears the full finance cost consequences of any delay in construction completion, the contractor is incentivised to complete the project on time. As with conventional 'fixed price/no progress payments' contracts, completion delays are therefore less common than for other conventional procurement methods.
Because the contractor is interested in minimising whole of life costs, the contractor has an incentive to ensure that the asset is built to an optimal quality standard. The client (ie, the government) therefore needs to put less effort into monitoring construction standards than is the case with conventional procurement methods.