شبیه سازی مدل فازی برای ارزیابی موارد امتیازی طرح های مشارکت بخش خصوصی و دولتی

The investment return, tariff regime and concession period are the most important items that influence the success of a concession-based public–private partnership (PPP) project. From the public partner's perspective, whether a scheme is value-for-money or not dominates the decision-making process. However, a seemingly favorable deal may turn out to be the least value-for-money option should it cause unnecessary social upheaval, such as excessive tariff increases or complaints. A scheme which is truly value-for-money is one which balances the interests of the public partner, investor and end-users. In this paper, a simulation model is proposed to assist a public partner to identify the concession period based on the expected investment and tariff regime. The needs for establishing different scenarios to represent the risks and uncertainties involved are presented, and a fuzzy multi-objective decision model is introduced to trade-off the associated three concession items. The combined features of the simulation and fuzzy multi-objective decision models enable the scenario most likely to result in a “win–win–win” concession scheme to be identified. A hypothetical example is used to illustrate the proposed model. This highlights the importance of the decision-makers’ perception of the concession items in influencing their selection, and the influence of the group decision-making involved.

An increasing number of construction industry stakeholders are striving to exploit the potential of opening up publicly owned and operated facilities/services to the private sector. Public–private partnerships (PPP) offer one means of achieving this by attaining a “win–win–win” situation among the government, business sector and end-users (cf: [1] and [2]). In fact, there is no shortage of successful PPP examples [3], [4], [5], [6], [7] and [8]. These have often provided significant overall cost savings for the project [9], [10], [11] and [12], more timely delivery of facilities/services [13] and better productivity performance and innovation [14]. In one of the most popular PPP alternatives, the concession scheme, the investor raises the necessary funding and provides the physical facility as well as maintaining and operating the completed asset [15]. In return, they recover their capital investment according to the terms set out in the concession agreement viz. the concession period, a proposed tariff regime and an expected investment return [16]. To ensure the scheme is financially viable and attractive, the investor might seek to initiate a higher expected investment return especially when the concession period is short. With an assured minimum profit proviso, the concessionaire may increase the tariff in case the scheme fails to reach its expected investment return. Yet, any upward adjustment in tariff will attract criticisms from the user and pressure groups. From the government's perspective whether or not a PPP scheme is of value-for-money is the prime concern; and those with unrealistically high expected returns and/or excessively lengthy concession periods may be conceived as a transfer of interest [17]. Hence, there is a legitimate need to balance the interests of all the stakeholders before a concession agreement is reached.

This paper proposes a method by which both simulation and fuzzy comprehensive evaluation can be combined to establish the most satisfactory concession item options for PPP projects. By incorporating the complex impact of risks involved, an appropriate concession period can be deduced by a simulation based on the minimum expected IRR and tariff regime. However, as the actual IRR and tariff regime would not be known at the proposal invitation stage, alternative scenarios need to be generated for consideration. The purpose of the fuzzy comprehensive evaluation process is to enable decision-makers to select the most preferable alternative from a list of possible scenarios, such that the concession period would be used for proposal invitation, while the corresponding tariff regime and investment return could serve as a basis for proposal evaluation at a later stage. The simulation process and the application of fuzzy theory have also been illustrated through a hypothetical example. The proposed simulation model could assist decision-makers establish a concession period for a PPP project that is acceptable to both the public and private partners; i.e. (i) to ensure the concessionaire gains a reasonable return, and (ii) to allow the public client to reclaim the facility at an appropriate time. After devising different possible alternatives of the concession items using the simulation technique, decision-makers could then evaluate the three concession items (i.e. IRR, tariff regime and concession period) of each alternative. The results would provide the fuzzy relations between the three items and alternatives. Then, through the fuzzy composite method, the non-inferior solution could be obtained to maximize the satisfaction of all the three parties.