Optimal capital structure of government-subsidized private participation in infrastructure projects

A government-subsidized private participation in infrastructure (PPI) project is a solution to attract private investors to invest in financially non-viable infrastructure projects with high social benefits. A government-subsidized PPI project comprises three financing sources: government subsidy, equity, and debt. For government-subsidized PPI projects, the government subsidy level must be determined before the optimal debt ratio can be determined. A government subsidy level that is too low may lead to the project being non-bankable for financial institutes and a level that is too high may result in high excess returns for project investors. This paper develops cooperative game models, which are multiple–variable game models, to determine optimal solutions for four major decision variables – the government subsidy, tariff, debt ratio, and interest rate for project negotiation for PPI projects. This three–party game model is developed to identify terms and conditions that optimize the total benefits of financially non-viable PPI projects, which can lead to successful PPI project negotiations. The Kaohsiung cable car project in Taiwan is used for demonstration purposes. The results of the analysis show that optimal solutions for the three financing sources - government subsidy, equity, and debt - can be determined by the models.