The most frequently used PPP model is the long term institutional-contract type PPP. Its main characteristic is provided by the (1) long duration of the relationship it established and partially regulates. Such long duration allows an (2) output specification of the performances of the private party and eventually the (3) bundling of the construction and operation phase. The long duration implies the occurrences of events that may have an impact on the service delivery as well as on the parties. That requires an efficient (4) risk allocation and (5) relation management.