We study the optimal design of Public-Private Partnerships (PPPs) when there is unobservable action on the private party's side. We show that if the private party does not have negotiating power over the project's surplus, then no inefficient delays are attributable to the moral hazard issue. However, if the private party has negotiating power, then the first-best timing is not guaranteed. The time discrepancy is shown to be costly in terms of overall project efficiency. The explicit consideration of the private party's negotiating power can explain empirical evidence that private parties in PPPs tend to reap excess returns. These results are discussed in light of the COVID-19 pandemic and its implications for PPPs.

我们研究了当社会资本一方有不可观察的行动时公私合作伙伴关系 (PPP) 的优化设计。我们表明，如果社会资本没有对项目盈余的谈判权，那么道德风险问题就不会造成低效率的延误。但是，如果社会资本具有谈判权，则无法保证最佳时机。就整体项目效率而言，时间差异被证明是代价高昂的。对社会资本谈判能力的明确考虑可以解释经验证据，即 PPP 中的社会资本往往会获得超额回报。这些结果将根据 COVID-19 大流行及其对 PPP 的影响进行讨论。