Sustainable and Optimal "Uniqueness" Contract in Public-Private Partnership Projects of Transportation Infrastructure

To control the "uniqueness" risk in Public-Private Partnership (PPP) projects of transportation infrastructure, we design a simplified "uniqueness" contract model by incorporating the impact of the initial investment which is based on the Bertrand model. The nonlinear programming method is adopted to derive the optimal "uniqueness" contracts for incumbent private capital, the public, and the social welfare, respectively. The simulation results show that the achievement of the optimal "uniqueness" contract is essentially the result of a compromise between the private capital, the public, and social welfare. The extent to which such a contract reduces the probability of "uniqueness" risk mainly depends on the equilibrium relation between the interests of private capital and the public. The initial investment is not related to the government default when the contract does not take into account the interests of the private capital. Furthermore, the "uniqueness" contracts between private capital and the government are mainly for anticompetitive purpose in the PPP market of transportation infrastructure. Unless the contract terms focus on the improvement of social welfare, entering a "uniqueness" contract will cause social welfare losses.