Optimizing the concession period of PPP projects for fair allocation of financial risk
Authors: Jin Hongyu , Liu Shijing , Liu Chunlu , Udawatta Nilupa 
Published: July 2019

Purpose
Targeting public–private partnership (PPP) projects, the purpose of this paper is to help decision makers fairly allocate financial risk between governments and private investors through a properly designed length of concession period.

Design/methodology/approach
On the one hand, the length of the concession period should be long enough to help private investors to achieve their expected profits. On the other hand, the length of a concession period cannot be decided without agreeing on an upper limit, since an overlong concession period takes too much time for governments to recover their investment and leads to an overly lucrative condition for private investors. Following this logic, the concession period decision range is decided, which defines the lower and upper limits for the length of the concession period. The net present values (NPVs) for governments and private investors are estimated via Monte Carlo simulation to better reflect the uncertainties. To further decide on the optimal length of the concession period, the principle of fair risk allocation between governments and private investors is adopted. The concession period, as an important project parameter, should help to minimize the financial risk gap between governments and private investors.

Findings
The developed concession period determination process is validated using a numerical example of a PPP transportation project. The analysis outcomes show that the proposed methodology is capable of determining the length of the concession period so as to control private investors’ profit within a reasonable range while achieving a fair allocation of financial risk between governments and private investors. The outcomes also indicate that, before determining the optimal length for the concession period, governments may need to make a choice between better financial risk allocation or stringent profit control for private investors.

Research limitations/implications
The determination process developed here may be inapplicable to social infrastructure PPPs where the income stream is less predictable. In addition, the data analysis targets a highway project with a capital subsidy provided by the government. To strengthen the effectiveness of the proposed determination process, further research should apply the model to PPPs with other kinds of government support.

Originality/value
The concession period for a PPP project is an important parameter and it is a common practice for governments to predetermine the length of the concession period before inviting tenders. The existing models for determining the concession period focus too much on the simulation of NPVs for project parties and neglect the importance of risk allocation in signing and maintaining a long-term contract. There is also a lack of research to evaluate the influence of governments’ preferences on the length of the concession period. To overcome the limitations of the existing models and enrich the methodology for concession period determination, this paper contributes to the body of knowledge by developing a concession period determination process which can help governments to make better decisions. The financial risk is expected to be more evenly shared between governments and private investors with the concession period derived from the proposed process. This determination process is also capable of evaluating the influence of governments’ preferences on the length of the concession period.