1

AN ECONOMIC FRAMEWORK FOR COMPARING PUBLIC-PRIVATE PARTNERSHIPS AND 

CONVENTIONAL PROCUREMENT

U.S. Department of the Treasury

Office of Economic Policy

May 2016

Abstract

In spite of its potential to benefit taxpayers, procurement of infrastructure through a publicprivate partnership (PPP) can be complex and difficult to structure. Indeed, partly reflecting 

these challenges, experience with PPPs in the United States is limited, which may be selfreinforcing by deterring public sponsors not familiar with PPPs from ever considering one to 

procure infrastructure assets.

This discussion paper aims to demystify infrastructure PPPs by explicitly describing the 

conditions under which a PPP can be a better choice for procurement over conventional methods 

from the perspective of how economists typically look at these issues. No single factor

definitively informs whether a PPP is likely to yield higher benefits to society and the taxpayer 

than conventional procurement. Instead, a balance of elements – the project’s characteristics, the 

economic environment in which the project is being developed, and the ability of the project 

sponsor to take certain actions – jointly determines whether a PPP’s delivery and operation of the

project is mutually beneficial to both the public and private sectors. 

This paper also describes important steps for a government sponsor to take before a project being 

procured through a PPP is started. An essential prerequisite to achieving the potential net 

benefits of a PPP is for the government sponsor’s to fully understand the project’s characteristics 

and economic environment before initiating the procurement. In addition, successful PPP 

implementation requires executing a set of complementary best practices before the project gets 

underway. Not taking these steps may lead to higher costs, failure to meet performance targets 

later in the project’s life cycle, and a misallocation of scarce public resources.
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I. Introduction 

Infrastructure investment can play a vital role supporting economic growth and prosperity in 

America. 1

 The challenges of paying for and managing infrastructure investment, on top of 

grappling with tighter budgets at every level of government, mean that the development of sound 

innovative financing methods is more important than ever. The Administration has embraced the

opportunity to encourage such development through the Build America Investment Initiative

(BAII), which is designed to expand private investment and public-private collaboration in major 

infrastructure sectors. Among other activities, the Initiative strives to raise awareness regarding

the appropriate use of well-designed public-private partnerships (PPPs) for providing and 

managing infrastructure assets and associated services that have traditionally been provided by 

the public sector.2 A major Initiative milestone occurred when the President signed the Fixing 

America’s Surface Transportation Act (FAST) last summer; FAST established a National 

Surface Transportation and Innovative Finance Bureau at the Department of Transportation to 

collaborate with the public and private sectors in the development of best practices for innovative 

financing and PPPs. 

Under a PPP, the government contracts with a private firm to take on a set of roles for an 

infrastructure asset involving its design, financing, construction, operation, and maintenance (or 

any subset of these roles) on behalf of the public sector. The gains potentially realized by society 

from procuring an infrastructure asset through a PPP rather than through a “conventional 

procurement” are induced by the transfer of responsibility for multiple project phases to a single 

private-sector entity. These potential gains include cost savings, higher service quality, and 

accelerated project delivery.

In spite of this promise, PPP procurement may be underused because it can be complex and 

difficult to structure. One complication is that the procurement must allow for joint benefits to 

the public and private sectors while also supporting the level of infrastructure investment that 

most benefits society and the economy. Moreover, given the robust municipal bond market in 

the United States, experience with PPPs in the United States is thus far limited. As a result, 

many public sponsors are not yet comfortable with assessing the relative benefits of PPP 

alternatives versus conventional procurement. Indeed, limited experience with PPPs – and 

attendant lack of knowledge about PPPs – may deter public sponsors from ever considering one

to procure infrastructure assets. 

The purpose of this discussion paper is to help fill this gap in knowledge by explicitly describing

the conditions under which a PPP can be a better choice for procurement over conventional 

 1 This paper was authored by Jane Dokko, Owen Kearney, and Neal Stolleman.

2 See, for example, U.S. Department of the Treasury. Office of Economic Policy. 2015. Expanding the Market for 

Infrastructure Public-Private Partnerships: Alternative Risk and Profit Sharing Approaches to Align Sponsor and 

Investor Interests.

https://www.treasury.gov/connect/blog/Documents/Treasury%20Infrastructure%20White%20Paper%20042215.pdf

(accessed April 5, 2016); and U.S. Department of Transportation. Federal Highway Administration. 2016. 

Successful Practices for P3s: A review of what works when delivering transportation via public-private 

partnerships. https://www.transportation.gov/sites/dot.gov/files/docs/P3_Successful_Practices_Final_BAH.PDF

(accessed April 5, 2016).
3

methods using an organizing framework based on of how economists typically evaluate these 

issues. The target audience for this discussion is those in state and local government who may be 

interested in PPP procurement but who are less familiar with this form of procurement of public 

infrastructure. However, even more-experienced officials may find that reviewing this document 

will sharpen their decision-making. The discussion assumes that the project underlying the 

procurement decision has a positive economic rate of return that makes acquiring the 

infrastructure asset worthwhile but there is uncertainty as to whether a PPP or conventional 

procurement yields higher net benefits to society.

In short, a balance of elements – the project’s characteristics, the economic environment in 

which the project is being developed, and the ability of the project sponsor to take certain actions

– jointly determines whether a PPP can deliver and operate a project that yields higher social 

welfare3 than would have been the case under conventional procurement. In other words, no one 

single factor informs whether a project yields a higher net social benefit as a PPP than under 

conventional provision, while providing a competitive rate of return for the private partner.

This paper also describes important steps for a public sponsor to take before a project being 

prodcured through a PPP is started. An essential prerequisite to achieving the potential net

benefits of a PPP is for the public sponsor to fully understand a project’s characteristics and

economic environment before initiating either type of procurement. In addition, successful PPP 

implementation requires executing a set of complementary “best practices” before the project 

gets underway.

Section II provides background information on conventional procurement and PPPs while 

Sections III describes the attributes of a project and the economic environment that would make 

an infrastructure project amenable to provision via PPP. Section IV discusses the best practices

that maximize the net benefits of a PPP, highlighting that the public sponsor should determine its 

capability to execute and enforce these procedures when choosing between conventional 

procurement and a PPP.4

 3 The term “social welfare” is a concept used in economics to mean the difference between the value consumers 

place on the infrastructure service and the resource costs of providing the service (which reflect the opportunity cost 

of not using these resources in their best alternative use elsewhere in the economy). There are two subparts to the 

concept: (1) the difference between the value consumers place on the service and what they have to pay to receive it, 

called “consumer surplus”, and (2) the difference between the revenue received by the infrastructure service 

provider and its incremental costs, called “producer surplus”. The value consumers place on the service reflects 

both its basic characteristics and quality level initially written into the contract, plus enhancements to quality that 

occur due to implementation of technical innovations after the project gets underway. When we refer to the 

“benefits of quality,” we mean the impact of new innovations on the value consumers place on the service, and their 

consumer surplus, but will not explicitly mention these terms. 4 Many topics are outside the scope of this note but are nonetheless important. Such topics include the process by 

which enabling legislation for PPPs is designed and implemented, functions and responsibilities of centralized PPP 

units, details of setting up a PPP project management office, the risk management and risk analysis process, and 

conducting a value-for-money analysis. For resources on these and other related topics, see U.S. Department of 

Transportation. Federal Highway Administration. 2016. Successful Practices for P3s: A review of what works 

when delivering transportation via public-private partnerships. 

https://www.transportation.gov/sites/dot.gov/files/docs/P3_Successful_Practices_Final_BAH.PDF (accessed April 

6, 2016); and Virginia Department of Transportation. Office of Transportation Public-Private Partnerships. 2011. 

PPTA Value for Money Guidance. http://www.virginiadot.org/office_of_transportation_public-
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II. PPPs and Conventional Procurement: Evaluating Infrastructure Procurement 

Alternatives

In the United States, publicly owned infrastructure assets are typically designed, constructed, 

operated, and maintained through a conventional procurement, in which the government owns 

the asset but the sponsoring agency separately contracts for each service, often from different 

private firms.5

 With competitive bidding, this approach allows the public sector to have 

qualified private firms fulfill the requirements of various project phases; however, contracted 

parties have very limited incentives to minimize lifetime project costs and instead will minimize 

only those costs that they incur during the respective single phases in which they are involved. 

Under conventional procurement, the public sponsor retains all revenue streams (net of project 

costs) and has direct control over most aspects of the project (subject to its budgetary 

constraints); the sponsor also assumes most of the project risks. 

By contrast, under a PPP, the government contracts with a single private entity (generally 

structured as a special purpose vehicle, or SPV)6 to complete, over a period of time that typically 

spans decades, multiple stages of a project: design, construction, operations and maintenance 

(O&M), and decommissioning. Depending on how the PPP is structured, the private partner

may also be responsible for financing the project, in which case a mix of debt and equity 

investors will participate in the project over its life-cycle. In exchange for assuming these 

responsibilities and risks, the SPV will receive a stream of revenue during the life of the contract, 

where the revenue stream typically takes the form of either user fees that the SPV collects 

directly from consumers of the infrastructure service, or availability payments, which are fixed 

periodic payments that the government pays to the private partner as long as performance, safety 

and quality standards are met, regardless of usage.

7

 These arrangements are not monolithic –

PPPs can vary in the extent to which they transfer responsibilities from the public to the private 

sector. Realizing the lower overall costs and higher quality from an infrastructure asset procured 

as a PPP will depends on both the specific attributes of the project and the ability of the public 

sponsor to take certain actions.

 

private_partnerships/resources/VDOT%20VfM%20guidance%20document_final_20110404.pdf (accessed April 6, 

2016); Virginia Department of Transportation. Office of Transportation Public-Private Partnerships. 2011. PPTA 

Risk Analysis Guidance. http://www.p3virginia.org/wp-content/uploads/2015/03/PPTA-Risk-GuidanceDocument_9.30.2011_Old-Version.pdf (accessed April 6, 2016); PPP Canada. 2012-2013. Annual Report –

Delivering Value for Taxpayers. http://www.p3canada.ca/~/media/english/annual-reports/files/2012-

2013%20annual%20report.pdf; and World Economic Forum. 2013. Strategic Infrastructure Steps to Prepare and 

Accelerate Public-Private Partnerships. 

http://www3.weforum.org/docs/AF13/WEF_AF13_Strategic_Infrastructure_Initiative.pdf (accessed April 6, 2016). 5 In some cases, the responsibility for operating and maintaining the infrastructure asset may reside with a different 

government agency than the one that contracts for its design and construction.

6 We will also sometimes refer to this entity as a consortium or concessionaire. The private partner establishes an 

organization called a special purpose vehicle (SPV) for the single PPP transaction, the operations of which are 

limited to construction, financing, and operation of the infrastructure asset under the PPP contract. In this paper we 

will use the term concessionaire and PPP interchangeably.

7 See page 2 of Engel, Eduardo, Ronald D. Fischer, and Alexander Galetovic. The Economics of Public-Private

Partnerships. New York: Cambridge University Press, 2014.
5

Regardless of the method of procurement chosen – conventional or PPP – an infrastructure asset 

still must ultimately be funded by a combination of tax revenue and user fees. PPP procurement 

is not a funding mechanism for public infrastructure, but a financing tool: as stated above, the 

private entity requires a revenue stream in order to provide and operate the infrastructure asset 

under a PPP, either from direct payments to the PPP by the sponsoring government, or from user 

fees collected by the concessionaire8 that the sponsoring government would otherwise have 

collected.9 Conventional procurement relies on the same sources of funding. In the United 

States, the majority of publicly owned infrastructure assets are currently financed by (1) federal 

grants and direct loans, federal loan guarantees. state and local expenditures, and general 

obligation bonds, and are therefore ultimately funded by tax revenues; and (2) revenue bonds 

backed by user fees, such as tolls, fees and charges, generated by enterprise systems such as toll 

roads, water and sewer systems, airports and public power utilities. 

When a PPP either lowers the costs incurred over the life of the project (while maintaining 

quality standards) or raises quality (without offsetting increases in cost), a PPP may be a more 

suitable form of procurement than conventional methods. The chief mechanism for inducing 

cost savings in a PPP is “bundling,” or the transfer of responsibility for several distinct project 

stages by the public sector to a single private sector entity.10,11 Bundling may encourage costsavings in at least three important ways. First, it provides incentives to the private partner to 

minimize costs across project phases by, for example, making investment choices in the design 

or construction phase that may lower costs in the O&M phase. The incentive to minimize lifecycle costs arises because the PPP contract both holds the private partner responsible for paying 

the unknown future costs of completing various project phases and endows the private partner 

with full decision-making authority and control of the asset in completing those phases. These 

incentives are absent under conventional procurement, where a single party does not have 

responsibility for more than one stage of the project and taxpayers bear most, but not all of the 

 8 The term concessionaire refers to the case where a public authority assigns to a private company the right to 

provide a monopoly service by charging users, usually through making investments at its own risk. This means the 

private party is offering a service directly to the public and taking end user risk. In this paper, we will sometimes use 

the term concessionaire and PPP interchangeably because a contract may allow for the private firm to receive a mix 

of payments from both end users and the government. See Public Services International Research Unit (PSIRU). 

Terminology of Public-Private Partnerships (PPPs). March 2003. http://ppp.worldbank.org/public-privatepartnership/overview/what-are-public-private-partnerships. 9 User fees set by the concessionaire would have to cover the private firm’s rate of return on capital, which are likely 

to be higher than the public sector’s financing costs, as discussed below. However, a well-structured PPP will have 

lower life-cycle costs than a conventionally procured project, mitigating the need for higher fees. 10 The term “bundling” can also have another meaning in the context of PPPs: “...contracting with one partner to 

provide several small-scale PPP projects in order to reduce the length of the procurement process as well as 

transaction costs.” Here, we use “bundling” to mean the transfer of multiple types of project stages to the private 

sector. See page 17 of Deloitte Research. “Closing America’s Infrastructure Gap: The Role of Public-Private 

Partnerships,” 2007. 

http://worldbank.mrooms.net/file.php/251/docs/optional_readings/Closing_America_s_Infrastructure_Gap.pdf

(accessed April 5, 2016).

11 Specifically, bundling can result in improved quality of the initial asset and improved service quality during its 

useful life. In principle, the government sponsor can set up a project through “public bundling”, analogous to a PPP. 

However, this approach tends to weaken incentives to lower the project’s life-cycle costs. See Engel, Eduardo, 

Ronald D. Fischer, and Alexander Galetovic. “Public-Private Partnerships: When and How.” Working paper, Yale 

University (2008). 
6

project’s risks, including those the government may not be well-positioned to influence.

12 

Second, bundling may lower the public sponsor’s costs of monitoring the private entity’s actions. 

Whereas conventional procurement requires contractual relationships with each one of multiple 

private entities, a PPP requires fewer contracts that, if the fixed costs of structuring and enforcing 

these contracts are large, may lead to lower public sector monitoring costs. Finally, bundling can 

also reduce costs through accelerated project delivery; if the private partner is responsible for the 

construction, operation, and financing of the project, and receives a share of project revenues, 

then it will have increased incentives to complete construction and begin operation as early as 

possible in order to start providing a given return to both debt and equity investors.

Generally, the incentive for generating cost savings is strengthened as the number of related 

phases that can be appropriately transferred to the private partner increases, and as the 

relationships between project phases become more complex. For example, the “design-build” 

(DB) contract transfers both the design and construction phases, which encourages the private 

partner to design the project so as to minimize building costs and the likelihood of design flaws. 

The “design-build-operate-maintain” (DBOM) model additionally encourages the private partner 

to select building methods and materials that minimize O&M costs, while the “design-buildfinance-operate-maintain” (DBFOM) structure also provides incentive for the private partner to 

reach the operations phase as early as possible to begin paying back investors.

Whether a government sponsor selects provision via conventional procurement or PPP, the 

project will incur costs and generate benefits.13 Conceptually, costs include, but are not limited 

to: material, labor, and equipment costs for installing initial capacity, O&M expenses, 

investments to improve cost efficiency and/or quality, and financing costs.14 The benefits of a 

well-structured PPP, though more difficult to measure, are at least as large as what users in the 

aggregate would be willing to pay to use the infrastructure asset. The preferred provisioning 

mechanism is the one that is expected to yield a higher stream of (discounted) benefits net of the

(discounted) stream of costs for the project. As we will discuss further, the relative magnitudes 

of these costs and benefits will depend on the project’s characteristics and economic 

environment and the actions of the public sponsor.

 12 For discussions of why the government might have difficulty achieving cost savings across project phases on its 

own, See Hall, John. “Private Opportunity, Public Benefit?” Fiscal Studies 19, no. 2 (1998): 121-140; and Engel, 

Eduardo, Ronald D. Fischer, and Alexander Galetovic. “Public-Private Partnerships: When and How.” Working 

paper, Yale University (2008). 

http://www.econ.uchile.cl/uploads/publicacion/c9b9ea69d84d4c93714c2d3b2d5982a5ca0a67d7.pdf (accessed April

5, 2016). 13 It is also possible for an infrastructure asset to be provided and operated solely by the private sector, i.e. complete 

privatization, but we do not explore this case.

14 An important aspect of PPP procurement is that financing and transaction costs are higher compared to 

conventional procurement because projects cannot borrow as inexpensively as city or state governments and because 

technical expertise is required to write and negotiate the contracts.
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III.Determining PPP Suitability: Attributes of the Project and Economic Environment 

This section identifies key project attributes and conditions in the economic environment that 

help inform whether a PPP is likely to yield a higher present value of net benefits than 

conventional procurement. The organizing framework and characteristics are presented in Table 

1 below. For the most part, these attributes and conditions are known prior to the project being 

put out for bid, and the extent to which they are met can be assessed in an initial PPP screening 

process. For instance, as mentioned earlier, projects may vary in the number of phases or risks

that can be bundled, with the most comprehensive being DBFOM. Projects may also differ in 

the availability of private sector-expertise and the extent to which a potential private partner’s 

knowledge covers all, or just a portion, of the project’s life-cycle. 

To provide guidance in assessing the relative importance of these conditions, we characterize 

each one as being of “High” or “Medium” importance. The complete absence of any of the 

attributes characterized as having High importance means that procurement should favor 

conventional provisioning. Similarly, if all conditions are met, procuring the infrastructure asset 

through a PPP will likely yield a higher net benefit than conventional methods. As a general 

matter, conditional on the High importance factors being present, the presence of the factors 

identified as having Medium importance increases the likelihood of a PPP achieving a higher net 

benefit to society over conventional procurement. But, all told, whether a PPP is chosen will 

likely rely on a balance of conditions being satisifed and, because there will be uncertainty and 

the relative benefits of PPPs will be imprecisely measured, judgment will be necessary when 

determining PPP suitability for an infrastructure project.

The discussion in this section is most applicable to the cases of a proposed PPP set up as a 

DBFOM or DBOM.15 Importantly, the analysis covers publically provided infrastructure, such 

as roadway, transit, water supply and wastewater treatment systems, and excludes infrastructure 

assets that are generally privately owned and financed, such as telecommunications and electrical 

power.

 15 In the United States, between April 2012 and April 2015, DBFOM contracts were the most common type of PPP 

structure.
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Table 1. Attributes of project and economic environment that increase PPP suitability

Attribute 1: The potential exists for bundling the responsibility for multiple project phases with a 

single private entity

As explained in the previous section, the main opportunity for cost savings through a PPP is 

bundling, whereby the public sponsor transfers multiple project risks – e.g. design, construction, 

O&M, finance – to the concessionaire, which then has a strong incentive to capture savings 

across the project’s phases; for example, by performing high-quality construction, the 

concessionaire lowers later O&M costs by an amount that more than offsets the increase in 

construction costs. The discussion in the previous section presupposed that such savings are 

possible. If phases and risks cannot be bundled, however, then a PPP is much less likely to result 

in lower overall savings than conventional procurement. 

Attribute 2: Private-sector expertise in project delivery exists, especially for managing complex 

projects

The availability of private sector-expertise across all project phases is a highly important 

determinant of whether PPP procurement will achieve the maximum possible net benefit. In 

particular, the private sector may have an advantage over the public sector when a project is 

complex, such as when a mix of project management skills, technical expertise, sector-specific 

knowledge, life-cycle asset management, and project finance capabilities is necessary for 

successful execution. The absence of a potential private partner possessing the expertise to 

perform these functions across the project’s life cycle or the inability of a private partner to

effectively manage the risks allocated to it reduces the likelihood that PPP procurement yields a 

Attribute Importance Caveats

1 Potential exists for bundling High

2 Private-sector expertise in project delivery exists across 

most project phases High

3 Asset and/or service quality are contractible Medium

If asset and/or service quality are not 

contractible, then cost-cutting must 

not diminish quality

4 Project features high capacity and long-lived assets Medium

5 Capital and O&M costs can be accurately forecasted to 

some degree Medium

If forecasting these costs is not 

possible, then it must be feasible to 

allocate cost risk to the private sector

6 Unanticipated investments lower costs by more than they 

lower quality Medium

If this attribute is not met, then 

incentives must be developed to foster 

socially beneficial investments

7 There is scope for private sector innovation across the 

project life-cycle Medium

8 Potential private partners are willing to assume limited 

demand risk Medium
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higher net benefit compared to conventional procurement. This condition is more likely satisfied

if projects of similar size and scope have previously been successfully executed.

16 Moreover, if 

multiple potential private sector partners possess the necessary expertise, then bidding for the 

project is likely to be more competitive, allowing the public sector to capture more of the 

potential cost savings (though the overall net benefit from the project procured as a PPP need not 

be altered).

Attribute 3: Asset and/or service quality are contractible and enforceable

A properly structured PPP contract strongly encourages cost savings across the project’s lifecycle. But it is important for the private partner’s actions that lower costs to not come at the 

expense of lower service quality. If the public authority cannot clearly define and enforce 

service quality standards in the contract, i.e., if a quantifiable service level agreement cannot be 

incorporated into the contract, then other considerations are necessary to determine whether a 

PPP is an appropriate procurement option. 

For example, for infrastructure projects for which quality is not contractible and user fees are 

generally not collected (this includes many types of social infrastructure, such as schools and 

prisons), a PPP can still be the preferred choice if the chief impact of the concessionaire’s 

decisions is to lower life-cycle costs with relatively little or no effect on service quality.

17 If, on 

the other hand, user fees can be collected – though quality is still not contractible and the

infrastructure project has increasing returns to scale – then the private partner in a PPP may face 

incentives to unilaterally cut costs regardless of the effect on quality, which would make

regulated privatization – akin to a public utility –more suitable for the project. 

In designing a PPP contract with service quality standards, the public authority should also 

determine the degree to which measurable output or quality metrics are available. If “off-theshelf” metrics already exist – based on experience with the same type of assets in other projects –

these can be more readily incorporated into the contract. If new technical output or quality 

specifications must be developed because leading-edge technology is being used, it will add time 

and risk to the project, and also make enforcing the contract more challenging. As an 

intermediate case, converting existing specifications for similar assets into clearly defined 

stipulations should present less of a challenge. The closer quality metrics are to being “off-theshelf,” the easier it will be to write a performance-based contract.

Attribute 4: The project features high capital costs and long-lived assets 

As briefly mentioned earlier, the existing financing environment is not favorable to PPPs. First, 

private debt issued by a PPP consortium is generally subject to higher financing costs under 

 16 In situations where first-in-class expertise is not available at a reasonable price, a government sponsor may be 

inclined to consider using a less-expensive but less-qualified partner for the project. This path should be taken with 

extreme caution given the risks, such as the greater likelihood of delays and missed performance targets relative to 

conventional procurement, due to the limited expertise of the private partner. 17 For example, design of a prison with better lines-of-sight for staff can reduce the required number of security 

guards without diminishing the level of security provided. See, Iossa, Elisabetta and David Martimort. “The Simple 

Microeconomics of Public-Private Partnerships.” Journal of Public Economic Theory 17, no. 1 (2015): 4-48. 
10

current tax law than municipal bonds used to finance conventional infrastructure provisioning 

because 1) private debt generally has a higher default risk than bonds issued by governmental 

agencies, and 2) municipal bonds are exempt from federal income taxes, and generally exempt 

from state and local income taxes in the state where issued. Second, PPPs also tend to result in

higher transaction costs than conventional procurement because of the need to compensate 

additional external financial, legal, and technical advisors who plan and develop project 

specifications and documents and who participate in the procurement process.18 These added

costs must be weighed against the cost savings generated by the bundling in the PPP 

procurement.19 

Since PPP transactions costs tend to be fixed and are mostly independent of the size of overall 

project costs,

20 assets procured using a PPP need to be sufficiently large to generate the cost 

savings necessary to offset those transaction costs. In addition, smaller projects will find it 

difficult to attract large, institutional investors, such as pension funds, which do not view

investments in smaller projects as being worthwhile. In addition to financing opportunities, 

these investors also provide expertise in monitoring managerial effort to high capital-value 

projects. They may perform other due diligence functions as well, such as reviewing 

documentation, evaluating the project’s financial viability, and assessing the jurisdiction’s legal

and regulatory environment. But executing these due diligence functions has a cost, which

investors will not agree to incur unless there is a likelihood of earning a reasonable return on 

their efforts, which is more likely to be met the larger the project is.

21 

When an asset’s useful life matches its contract length, longer-lived assets, all else equal, allow 

for PPP contracts that are more likely to be mutually beneficial to the public and private sectors.

A longer-term contract allows the public authority to benefit from efficiencies and innovations

while the private partner can rely on a lasting source of revenue, such as availability payments,

that is both reasonably secure and sufficient to recover its investment while earning a 

competitive return.

22 Allowing for risk-sharing arrangements in a long-term contract could 

further help tilt the procurement decision in favor of a PPP for projects that collect user fees (see 

Attribute 8 below).

 18Unlike conventional procurement, a PPP consortium can consist of multiple private entities, each with its own 

need for external advisors. PPP Canada. 2014. Identifying PPP Potential – A Guide for Federal Departments & 

Agencies http://www.p3canada.ca/~/media/english/resourceslibrary/files/p3%20a%20guide%20for%20federal%20departments%20%20agencies.pdf (accessed April 6, 2016). 

19 PPP Canada. 2014. Identifying PPP Potential – A Guide for Federal Departments & Agencies 

http://www.p3canada.ca/~/media/english/resourceslibrary/files/p3%20a%20guide%20for%20federal%20departments%20%20agencies.pdf (accessed April 6, 2016). 20 See page 20 of Iossa, Elisabetta and David Martimort. “The Simple Micro-Economics of Public-Private 

Partnerships.” CEIS Tor Vergata Research Paper Series Vol. 6, Issue 12, No. 139 (2013): “...transaction costs are 

also to a large extent independent of the size of a project, which suffices to make PPP unsuitable for low capital 

value projects.”

21 See Iossa, Elisabetta and David Martimort. “The Simple Microeconomics of Public-Private Partnerships.” 

Journal of Public Economic Theory 17, no. 1 (2015): 4-48. 22 PPP Canada. 2015. Application Guide and Application Form, Round 7. 

http://www.p3canada.ca/~/media/english/resources-library/files/application%20guide%20round%207-

english%20final.pdf (accessed April 6, 2015).
11

Attribute 5: Capital costs and O&M costs can be forecasted with some degree of accuracy

Being able to forecast both construction and O&M costs (including the labor component) over 

the duration of the long-term contract with some precision is desirable. The PPP contract 

commits the private partner to covering costs and meeting schedules over the long term and 

commits the public authority to assuming responsibility for the total costs of the project should 

the SPV fail. The public authority should ascertain whether long term O&M needs are relatively 

stable and predictable, based on established technologies and historical demand patterns, such as 

they exist. If these are not well understood because leading-edge technology will be used and/or 

there is significant demand uncertainty, then the project sponsor will be more vulnerable to the 

risk that subsequent opportunistic contract renegotiations will result in additional 

reimbursements from the government to the private partner. 23 Moreover, forecasts of O&M 

costs should limit the scope for cost reductions to occur through wage and benefit reductions, 

and should generally incorporate the need for strong labor standards.

For infrastructure projects that collect user fees, flexible PPP contracts that contain profit-sharing 

provisions can mitigate the private sector’s construction cost risk and O&M cost risk by shifting 

a mutually acceptable portion of the risk to the public sponsor, reducing the likelihood of 

bankruptcy or costly contract renegotiation. A higher probability of renegotiation also induces 

moral hazard on the part of the concessionaire; the more likely the private partner is to be 

reimbursed for its costs, the weaker are the cost-saving incentives fundamental to a PPP.

Attribute 6: There is the possibility of investments that are unknown at the time of contracting 

but will later lower costs more than quality along with being implementable and observable 

Even if quality standards can be clearly defined by the project sponsor at contract signing, 

investment opportunities affecting service quality and life-cycle costs will often arise

subsequently that could not have been written into the contract prior to execution for any number 

of reasons. In this way, PPPs are “incomplete” contracts, that is, they cannot specify actions and 

 23Under conventional procurement, the public authority implicitly self-insures against unexpected cost shocks. 

When making a comparison with PPP procurement in a value-for-money analysis, the imputed value of the 

insurance premium should be added to conventional project costs. A PPP is generally able to purchase insurance to 

cover a number of project risks, such as covering equipment and materials up to delivery to the site, a Construction 

all-risk (CAR) policy that covers operations and assets on site during the construction phase, or liability insurance 

for claims by third parties. World Bank Group. Public-Private Partnership in Infrastructure Resource Center. 2015. 

Insurance Checklist Explanatory Note. http://ppp.worldbank.org/public-privatepartnership/sites/ppp.worldbank.org/files/documents/insurance_checklist_explanatory_note_en.pdf (accessed April 

6, 2015); Insurance companies are increasingly able to offer insurance against risks in PPP projects insofar as they 

are defined and standardized in regular insurance packages. “Regular” risks are relatively typical risks that the 

market is willing to accept or insure against. Any risks that go beyond what the insurance industry is willing to 

accept can be thought of as “extraordinary”. It may become difficult or very expensive to obtain insurance that 

covers risk outside of regular packages. International Institute for Sustainable Development (IISD). 2015. Risk 

Allocation in Public-Private Partnerships: Maximizing value for money. 

https://www.iisd.org/sites/default/files/publications/risk-allocation-ppp-maximizing-value-for-money-discussionpaper.pdf (accessed April 6, 2016). Without insurance, the private partner would have to absorb all or some of an 

unexpectedly large increase in cost, increasing its risk exposure. For this reason, it is possible the private sector may 

make overly conservative cost estimates in an effort to win the bid, with the expectation that it will be able to recoup 

higher than expected cost increases through renegotiating the contract with the sponsor.
12

payments for all possible contingencies.24 Although these contracts can be incomplete for 

different reasons, for our purposes, we focus on investments that are uncertain at the time of 

contract execution but are observable after they are implemented. For example, an investment 

made by the private partner would have been uncertain to the public sponsor at the time the 

contract came into force if the technology had not yet been developed then. This means that the 

public sponsor cannot enforce the contract until after the investment has been completed, when 

the effects of the technical innovation on service quality and life-cycle costs can be observed. In 

other words, a technological innovation occurring after the contract signing may give rise to 

investment opportunities that could not have been anticipated at the time of signing, but which 

would have been written into the contract had they been foreseeable.

25 For instance, the 

development of a highly energy-efficient heating system that would lower fuel consumption and 

pollution may occur after the contract to build a hospital is awarded.

The socially optimal level of non-contractible investment balances benefits and costs at the 

margin, but in practice there may be either too little or too much because investment incentives 

need not be aligned for the government sponsor, the firm that builds the asset, and the firm that 

operates the asset. Private parties tend to more heavily weigh the effects of these investments on 

costs, while the sponsor more heavily weights their effects on social benefits.26 For example, 

conventional procurement may result in an overinvestment in quality, meaning that incremental 

investments in higher quality cannot justify their costs, which ultimately reduces the project’s 

net benefit. Alternatively, a PPP may implement a cost-cutting innovation for which the resulting 

savings are outweighed by the reduction in quality; that is, cost cutting can have a negative 

spillover effect on quality. Conversely, if the private partner is exclusively concerned with costcutting, it may invest less than is socially optimal by not considering the positive spillover effects 

that another type of cost-cutting investment might have on service quality. The best procurement 

choice will depend, in part, on whether the non-contractible investment opportunities that can be 

expected to arise during the contract term will have a larger effect on quality or costs.27

More specifically, a PPP is more appropriate when there is an expectation that non-contractible

investments that affect cost more than quality will be possible during the contract term. If this is 

not expected to be the case, a system of enforceable rewards and penalties can be used to steer 

the level of future non-contractible investment toward the socially optimal level. For example, 

linking the concessionaire’s compensation to achieving measurable output or service quality

 24 Klein, Peter G. “Incomplete Contracts.” Palgrave Macmillan (2015). 

http://www.palgraveconnect.com/esm/doifinder/10.1057/9781137294678.0287 (accessed April 5, 2016). 25 Although it is not the only approach for conceptualizing investments under incomplete contracts in the context of 

PPPs, we adopt the framework of Bennett, John and Elisabetta Iossa. “Building and managing facilities for public 

services.” Journal of Public Economics 90, no. 10-11 (2006): 2143-2160. See page 2145: “...we model 

investments by the firms as the undertaking of research into innovative approaches to carrying out their respective 

tasks. Such investments are noncontractible ex ante but verifiable ex post: whilst it is not possible to contract ex 

ante on the delivery of an innovation, once a potential innovation has been discovered, its implementation is 

verifiable.”

26 See page 126 of Dewatripont, Mathias and Patrick Legros. “Public-private partnerships: contract design and risk 

transfer.” EIB Papers 10, no. 1 (2005): 120-145. 

http://www.eib.org/attachments/efs/eibpapers/eibpapers_2005_v10_n01_en.pdf#page=96 (accessed April 13, 2016). 27 It is also important to recognize that this decision will also depend on the types of non-contractible investments

the public sponsor thinks will be available to and feasible for the private partner.
13

outcomes can compensate for investment shortfalls by providing a monetary incentive to 

undertake additional quality-enhancing non-contractible investment that also reduces life-cycle 

cost (or that increases life-cycle cost by less than the value of the additional quality). Similarly, 

penalties that reduce compensation for failing to achieve or maintain service performance targets 

can discourage socially wasteful overinvestment in cost-cutting technology that otherwise would 

lead to excessive reductions in quality. For more details about PPPs in the context of incomplete 

contracts, see the appendix at the end of this document.

Attribute 7: There is scope and incentive for private sector innovation not present with 

conventional procurement 

The scope and incentive for private sector innovation will depend heavily on the extent to which 

performance-based contracts are used to specify features of the infrastructure asset or the service 

it provides. Performance-based contracts maximize the private sector’s incentive to use 

innovative approaches to achieve the specified outcome at the least cost, and depend on the ready 

availability of quantifiable output/quality measures.28 As discussed above, if output and quality 

measures are not contractible, then conventional procurement may be preferable, particularly if 

the level of service quality is sensitive to the actions taken by the private partner to lower costs. 

Moreover, if the public sector believes as a matter of policy that it must rely on prescriptive input 

specifications rather than allow the private partner to independently make those decisions, then 

the potentially greater benefits of PPP procurement are unlikely to be realized, and conventional

provisioning would be preferable. The public sector’s preference for defining the inputs will 

depend, in part, on the type of project under consideration; for example, the sponsor may want or 

need to exert tight control over a project with stringent security requirements, making a PPP 

unattractive or unfeasible. 

Attribute 8: Potential private partners are willing to assume limited demand risk in projects with 

user fees as a funding source

It is conceivable that a project could have a higher expected net benefit as a PPP, but that no 

potential private partner is willing to assume all demand risk when the revenue stream is based 

entirely on user fees, and no public sponsor is willing to assume all the demand risk when the 

revenue stream is based entirely on availability payments. A PPP might still be possible, 

however, if the private partner is willing to assume a portion of the demand risk through one of 

several risk-sharing arrangements that may be negotiated in the contract.

29 If the private sector is 

willing to share risk both on the project’s upside and downside, then the risk-return tradeoff may 

become more acceptable to the private partner (and at least as acceptable to the public sponsor). 

 28 PPP agreements are output-based in the sense that the public-sector party specifies basic capacity and quality 

standards but the private sector assumes responsibility over how to meet the specified output. See Iossa, Elisabetta 

and David Martimort. “The Simple Microeconomics of Public-Private Partnerships.” Journal of Public Economic 

Theory 17, no. 1 (2015): 4-48. 

29 See U.S. Department of the Treasury. Office of Economic Policy. 2015. Expanding the Market for 

Infrastructure Public-Private Partnerships: Alternative Risk and Profit Sharing Approaches to Align Sponsor and 

Investor Interests.

https://www.treasury.gov/connect/blog/Documents/Treasury%20Infrastructure%20White%20Paper%20042215.pdf

(accessed April 5, 2016).
14

In essence, PPP deals might be more attractive to investors if investors can exchange some 

upside demand risk for protection from downside demand risk. This type of contract flexibility 

increases the odds of the project’s success by reducing the likelihood of the SPV’s bankruptcy or 

costly contract renegotiation. It also has the benefit of aligning incentives of the project sponsor 

and investor, given that they both share in the project’s upside and/or downside potential.

IV.Best Practices for Successful PPP Implementation

The decision to procure a project as a PPP should be based on the expectation that it will yield a 

higher net benefit to the public sector than would have been the case under conventional 

procurement. Yet, a PPP is a more complex structure than a traditionally procured public 

infrastructure project, and for this reason, the public sponsor must undertake additional actions to 

support project execution prior to letting the contract out for bid in order to ensure that the higher 

net benefit is realized. These actions should be consistent with the economic principles 

enumerated above – allocating project risks to the party best able to manage them, optimizing 

life-cycle costs through bundling of project responsibilities, strengthening incentives for 

investors to participate in PPP projects, and introducing incentives that bring about socially 

optimal investment levels – in order to maximize the project’s expected net benefit.30 Not taking

these steps may lead to higher costs and failure to meet performance targets later in the life 

cycle.31 

 

These procedures can be grouped into four broad best practice areas. The first area includes 

practices that create a favorable enabling environment that aims to reduce transactions costs by 

establishing a predictable legal and regulatory climate and enhancing public sector capacity, 

which will increase investors’ incentives to participate in the PPP market. The second area 

involves practices that ensure a rigorous project preparation process that institutionalizes critical 

planning and monitoring functions, such as defining the strategic objectives of the project, and 

verifying that progress is being made consistent with the project plan. Implementing this 

practice area creates an incentive to select output and quality metrics that can measure progress 

and that are necessary for performance-based contracts; it also creates an incentive to minimize 

costs by avoiding costly scheduling delays due to poorly coordinated work streams. Moreover, 

the ongoing identification and tracking of emerging risks, which is part of the monitoring 

function, encourages development of effective risk-mitigation strategies.32 The third area 

involves conducting a bankable feasibility study that provides robust and high-quality analysis of 

the technical, commercial, legal, and environmental feasibility of the project in order to 

 30 This section lists actions that are appropriate after a project has passed both a cost-benefit analysis (i.e. it is 

expected to generate a positive net social benefit) and a value-for-money analysis (i.e. it is expected to cost less if 

organized as a PPP than would be the case if it was conventionally procured).

31 World Economic Forum. 2013. Strategic Infrastructure Steps to Prepare and Accelerate Public-Private 

Partnerships. http://www3.weforum.org/docs/AF13/WEF_AF13_Strategic_Infrastructure_Initiative.pdf (accessed 

April 6, 2016).

32 Organizationally, this requires setting up the project team and leadership, designing the project governance 

structure and project management, as well as securing required preparation funding.
15

demonstrate its financial viability.

33 The final area includes practices that would structure a 

balanced risk allocation in concert with regulatory protections in order to allow for a long-term 

partnership between the public and private sectors that balances efficiency incentives and publicinterest safeguards. 

 

In considering whether to go forward with a project as a PPP, the public authority should first 

determine its capacity to execute these best practices. If these capabilities are lacking, the public 

sponsor will require support from external consultants and advisors to conduct preliminary 

designs, develop technical and operating criteria, undertake traffic and environmental impact 

studies, and create preliminary financing structures, for example. In the following sections, we 

present each of the four practice areas in greater detail.34

Fostering a favorable environment for PPPs, including strengthening public sector expertise

This section describes the prerequisites that the public sponsor should put in place prior to any 

PPP procurement. Any jurisdiction seriously weighing infrastructure procurement via PPP 

should likely lay the groundwork in the form of PPP-enabling legislation, incorporating strong 

labor standards, institutions, and means for capacity building. Private investors are most likely 

to assume the risks stipulated in a PPP contract in a predictable and enforceable legal and 

institutional environment.35 Furthermore, the public sector cannot capably execute complex, 

 33 The environmental component of the feasibility study should include strategies for minimizing the risk of 

environmental damages due to the project.

34 This discussion distills information from several sources: World Economic Forum. 2013. Strategic 

Infrastructure Steps to Prepare and Accelerate Public-Private Partnerships. 

http://www3.weforum.org/docs/AF13/WEF_AF13_Strategic_Infrastructure_Initiative.pdf (accessed April 6, 2016);

International Bank for Reconstruction and Development. The World Bank. Asian Development Bank. InterAmerican Development Bank. 2014. Public-Private Partnerships Reference Guide Version 2.0. http://wwwwds.worldbank.org/external/default/WDSContentServer/WDSP/IB/2014/09/08/000442464_20140908133431/Rend

ered/PDF/903840PPP0Refe0Box385311B000PUBLIC0.pdf (accessed April 6, 2015); OECD. 2012. 

Recommendation of the Council on Principles for Public Governance of Public-Private Partnerships. 

https://www.oecd.org/governance/budgeting/PPP-Recommendation.pdf (accessed April 6, 2016); Urban Land 

Institute. 2005. Ten Principles for Successful Public-Private Partnerships. http://uli.org/wpcontent/uploads/2005/01/TP_Partnerships.pdf (accessed April 6, 2015); and Asian Development Bank. 2012. 

Public-Private Partnership Operational Plan 2012-2020. http://www.adb.org/sites/default/files/institutionaldocument/33671/ppp-operational-plan-2012-2020.pdf (accessed April 6, 2016). For additional information on the 

operational details of these practices, see U.S. Department of Transportation. Federal Highway Administration. 

2016. Successful Practices for P3s: A review of what works when delivering transportation via public-private 

partnerships. https://www.transportation.gov/sites/dot.gov/files/docs/P3_Successful_Practices_Final_BAH.PDF

(accessed April 6, 2016). 

35 A local jurisdiction’s statutory ability to implement a PPP may be circumscribed by the scope of the state’s PPPenabling legislation. Enabling legislation sets the framework under which a PPP project can be developed. Private 

participation in project development, financing, and operation must be legally possible. While not absolutely 

essential, well-crafted enabling legislation increases the prospects for PPP development because it will delineate the 

range of acceptable projects and the process for consideration and award. Legislation also signals to investors that 

the state is committed to this form of procurement, and lowers PPP transactions costs by standardizing the 

procurement process. Where legislative support is not available, or is limited, the design of a robust legal and 

regulatory framework will require cooperative effort across state and local jurisdictions, including formulation of an 

overarching PPP policy that sets down clear objectives and principles and defines a “roadmap” for implementation. 
16

multiphase transactions with the private sector without highly skilled staff possessing financial, 

legal, and negotiating expertise. Strong institutional capacity can be facilitated by disseminating 

standardized tools and knowledge products, policy formulation, and technical assistance. 

Depending on the degree of expertise within the jurisdiction, these types of functions could be 

carried out by PPP units established within state transportation departments or treasury/finance

departments. For transportation projects in particular, state and local governments can avail 

themselves of federal-level expertise and analytical tools through the Build America 

Transportation Investment Center (BATIC). Depending on the public authority’s size and 

technical capacity, many of the benefits of standardization and increased investor interest can be 

facilitated by formulating a steady project pipeline and an integrated infrastructure plan for the 

jurisdiction (or a multi-jurisdictional, regional plan, where projects span political boundaries).

36 

Finally, guidelines for an effective stakeholder engagement program are critical to a successful 

PPP implementation.

Managing a rigorous project preparation process

Fundamentally, the actions in this best practice area contribute to the avoidance of costly 

scheduling delays while also lessening the impact of unanticipated risks, two factors that 

diminish the expected net benefit of the PPP project. The preparation process involves multiple 

stakeholders: government agencies and bureaus ranging from federal to local levels, regulators, 

engineering firms, banks, investors, and users. It is important to assemble a capable, crossfunctional team with a well-defined and transparent governance structure that includes key 

stakeholders with well-defined roles and responsibilities. The team should cover a broad range 

of expertise, including sector-specific knowledge, project management, technical expertise, and 

project finance and deal-making experience.37 A project management office should be 

established to define a multi-stage project plan; coordinate and monitor interdependent work 

streams; and identify and track emerging risks. It is also important to obtain upfront funding for 

feasibility studies, so governments should establish project-preparation facilities, i.e. dedicated 

funds for feasibility studies. More generally, the public authority should standardize the projectpreparation process to the extent possible, by using common feasibility study guides, 

specification manuals, and draft concession agreements.

Credibly Assessing Project Feasibility

One benefit of having a credible feasibility study that demonstrates the project’s viability is that 

it reduces the risk of the project to the SPV, which improves its pricing of the overall 

 

Despite this daunting challenge, to the extent possible, local jurisdictions should leverage whatever flexibility they 

have to establish a predictable institutional framework. 

36 Regional efforts that leverage common infrastructure requirements and economic priorities may be able to achieve 

efficiencies in planning and creating political critical mass beyond what is possible on an individual basis, including 

harmonizing institutions and PPP governance. Advantage should be taken of any available legal flexibility. 37 For more information on the activities of this team, see U.S. Department of Transportation. Federal Highway 

Administration. 2016. Successful Practices for P3s: A review of what works when delivering transportation via 

public-private partnerships. 

https://www.transportation.gov/sites/dot.gov/files/docs/P3_Successful_Practices_Final_BAH.PDF (accessed April 

5, 2016).
17

procurement package to the sponsor. On the other hand, should the SPV fail financially, the 

public sponsor would then have to undertake the costly process of finding a new private partner.

The more likely this contingency is, the more likely it is that conventional procurement is the 

better choice from the perspective of maximizing the project’s net benefit. To be credible, a 

feasibility study must be undertaken to demonstrate that the project is a viable financial 

investment for the private partner, delivers net economic benefits to society, and possesses sound 

technical foundations. The study should include a sensitivity analysis for key risks, including 

possible setbacks due to stakeholder opposition or failure to obtain necessary permits or acquire 

needed land.38 Conducting a feasibility study is especially important if the private partner’s 

revenue is comprised entirely of user fees, where overly optimistic demand forecasts have led a 

number of PPPs to fail financially, particularly in cases of newly constructed toll roads. 

Therefore, in order to avoid “optimism bias” in the forecasts, it is critical to ensure the 

independence of the party making the forecasts, confirm that high quality data and methods are 

being used, and allow for forecasts to be challenged. 

Moreover, the public sponsor can take steps to increase the feasibility of a project. To provide 

an incentive for contractors to develop innovative solutions, output specifications should be

written into the contract (to the extent possible), and service requirements should be broadly 

defined to allow for competing technical solutions to be evaluated. And while user charges and 

availability payments are the major funding mechanisms, financial viability of projects located in 

high-density areas may be enhanced by considering ancillary revenues from retail operations or

from converting a portion of the increase in adjacent property value generated by the 

infrastructure investment into public revenue (via land value capture). Moreover, we note that 

when credit rating agencies assess PPP projects, including their effects on public sector finances, 

availability payments and other relevant costs and contingent liabilities are treated as long-term 

obligations on the public budget. Finally, the private partner should vigorously engage with 

stakeholders and have ample opportunity for due diligence that all parties feel that they had 

sufficient opportunity to raise possible concerns.

Structuring the PPP contract with a balanced risk allocation and regulatory protections

Under the assumption that an infrastructure project yields a net social benefit, a PPP will be 

mutually beneficial if it achieves a lower overall cost versus conventional procurement for the 

public sector and it generates a competitive rate of return for the private partner. Therefore the 

public sponsor should only transfer those risks that will induce the private partner to take actions 

that will increase the net value of the project (e.g., higher quality of service or lower per unit 

costs), which requires contractually allocating controllable risks to the party best able to manage 

them.39 Price changes should be regulated in the contract to limit any tendency for the private 

firm to overcharge, while the public authority can provide quality incentives through bonuses 

and penalties to motivate a socially optimal level of investment. The public sponsor can also 

take steps that change the risk-reward profile or mitigate risk to make PPPs more attractive. The 

 38 The feasibility study could be conducted by an established PPP unit or the sponsoring agency, with assistance 

from external financial advisors and technical consultants. 

39 If risks are allocated incorrectly, for example if the government cannot cost-effectively manage the risks it 

assumes, then the risk-reward balance will be skewed in favor of the private partner.
18

public authority might address investor dissatisfaction with a contract based strictly on either 

user fees or availability payments by transferring some, but not all, demand risk to increase the 

project’s attractiveness to both parties. For example, the public authority can use guaranteed 

minimum revenues while alleviating concerns about perceived excessive earnings through 

maximum revenue caps. The regulatory/contract system can also include adaptive mechanisms 

that self-correct against economic cycles or commodity price volatility, e.g. power-sector

regulations include pass-through clauses to dampen fuel cost volatility.40 Further, public sector 

intervention options should have triggers, for example, building a non-tolled road near a PPP toll 

road concession only if the latter has become severely congested; or specifying the conditions 

when refinancing should occur, such as a pre-specified debt-service coverage ratio.41 

Intervention should balance the public authority’s need for flexibility when economic 

circumstances change with the private sector’s need for predictability.

Much additional information concerning the operational details associated with best practices 

can be found in a BAII report entitled Successful Practices for P3s.42 The report provides very 

detailed and practical suggestions for public agencies in the early stages of establishing a PPP 

program; for example, it discusses the diverse characteristics of PPP-enabling legislation that 

exists in different states and provides an in-depth review of the organizational requirements for 

setting up a centralized PPP unit. Such practical considerations are outside the scope of this 

report. For instance, we generally assumed that the required PPP-enabling legislation was in 

place, and focused on the fundamental economic characteristics that make PPP procurement 

under a DBFOM – the most prevalent organizational form in the United States – preferable to 

conventional provisioning of infrastructure. But, we encourage potential project sponsors to read 

the BAII report to learn more about the operational details of implementing successful PPPs. 

Conclusion 

Infrastructure investment is vital for America’s continued economic growth and prosperity, 

especially given the significant infrastructure gap currently being faced by the nation. 

Constrained budgets at all levels of government have led to increased focus on sound innovative 

infrastructure financing methods. Public private partnerships represent a promising approach 

that can leverage the strengths of the private and public sectors to expand and improve our 

 40 See U.S. Department of the Treasury. Office of Economic Policy. 2015. Expanding the Market for 

Infrastructure Public-Private Partnerships: Alternative Risk and Profit Sharing Approaches to Align Sponsor and 

Investor Interests.

https://www.treasury.gov/connect/blog/Documents/Treasury%20Infrastructure%20White%20Paper%20042215.pdf

(accessed April 5, 2016).

41 The debt service coverage ratio measures the ratio of cash flow available to pay the debt service, divided by that 

debt service. If the ratio becomes too low, then the government may view refinancing at lower market interest rates 

as a prudent measure to lower recurring debt costs. 42 U.S. Department of Transportation. Federal Highway Administration. 2016. Successful Practices for P3s: A 

review of what works when delivering transportation via public-private partnerships. 

https://www.transportation.gov/sites/dot.gov/files/docs/P3_Successful_Practices_Final_BAH.PDF (accessed April 

5, 2016).
19

nation’s infrastructure. Yet, PPPs are not a good fit for all projects. In each case, the public 

authority must establish that a PPP would provide net benefits to society that go beyond what is 

attainable through conventional procurement alone, including a careful screening of projects for 

their suitability factors. Thereafter, successful PPP implementation requires executing a set of 

additional best practices before the project gets underway. Not taking these steps may lead to 

higher costs, failure to meet performance targets later in the life cycle and a misallocation of 

scarce public resources.

 
20

V. Technical Appendix: PPPs and Incomplete Contracts

Observable (and therefore verifiable) investments affecting service quality and life-cycle costs 

can be included in the PPP contract, but “non-contractible” investments that affect quality and 

life-cycle costs cannot be written into the contract prior to execution.

43

In order for the terms of a PPP contract to be enforceable, a court must be able to verify them as 

written into the contract (e.g. baseline service quality standards or the level of investment in 

infrastructure capacity). During the contract term, however, the private partner may face 

investment opportunities that could not have been foreseen when the contract was signed (due to 

technical innovation) but will affect service quality or life-cycle costs in observable ways;

44

these type of investments are called non-contractible. 

What determines the socially optimal amount of non-contractible investment, and why might it 

not be attained?

From society’s perspective, the optimal amount of non-contractible investment balances 

marginal investment cost with the marginal benefit of quality-enhancement and/or life-cycle cost 

savings.45 In practice, however, conventional provisioning and PPPs provide different 

investment incentives. For instance, under conventional provisioning the public sponsor is 

interested in the capital budget and innovations that improve quality and does not consider lifecycle O&M costs when making investment decisions (either O&M is separately contracted to a 

different private firm or, if carried out by the government, may fall under the operating budget 

with a separate dedicated funding source).46 Under a PPP, the private sector is focused on 

optimizing life-cycle costs given the nature of the PPP contract and is less attentive to potential 

quality improvements from possible investment decisions (unless quality incentives are included 

in the contract beyond the provision of a minimum quality standard) because it likely cannot 

capture any of the increase in users’ welfare through price increases under the existing contract 

absent any renegotiation. Given these differences in investment incentives, the choice of a PPP 

vs. conventional procurement will have different implications for the optimal level of 

investment. The choice of procurement method will depend in part on expectations over the 

 43 See footnote 25 for what is meant by the term “non-contractible” as we use it in this paper. 44 The effects of non-contractible investment on quality and life-cycle costs will not be observed until after the fact, 

at which point there may be ex-post renegotiations between the public authority and private partner to decide how to 

share the net benefits of the investment. 45 This explanation is based on a simplifying assumption that investment costs and benefits are continuous, i.e. they 

change in infinitesimally small increments, so that we can find an exact level of investment at which marginal 

benefit equals marginal cost, which characterizes the optimal level of investment in elementary economics. The 

same principle holds for “lumpy” investments that are made in discrete intervals, in which case investments are 

made as long as the marginal benefit exceeds the marginal cost of the next discrete unit of investment. 46 This is an assumption, and one that is generally not consistent with the usual approach, where the government’s 

objective function is the sum of consumer and producer surplus. See page 56 of Engel, Eduardo, Ronald D. Fischer, 

and Alexander Galetovic. “Public-Private Partnerships: When and How.” Working paper, Yale University (2008)

http://www.econ.uchile.cl/uploads/publicacion/c9b9ea69d84d4c93714c2d3b2d5982a5ca0a67d7.pdf (accessed April

5, 2016): “...we assume that the government is benevolent but for one defect, ignoring life-cycle costs when 

bargaining with the builder and considers only consumer surplus. This assumption is necessary because the case for 

bundling would be rather weak if governments would routinely internalize life-cycle costs.” 
21

different types of non-contractible investment opportunities that might arise and their relative 

impacts on service quality and life-cycle cost. 

A particular procurement method can induce too little or too much of the non-contractible 

investment when both quality and costs are affected.

It is possible that the level of investment will be too low. Under conventional provision, only 

the effect of investment on service quality is considered (see above). If the quality effect is 

positive, then certainly investment will be undertaken – up to the point where the marginal 

benefit of higher service quality equals marginal investment cost – with the benefits shared 

between the private builder and public authority.47 However, the total investment level will be 

too low compared to the socially optimal level because neither the builder nor the public sponsor 

considers the incremental benefit from making additional quality-enhancing investments that 

also lower life-cycle costs. In other words, investment is too low compared to the socially 

optimal amount because the joint marginal benefit of higher quality and saved costs is greater 

than the marginal investment cost. 

Next consider a PPP, in which the private partner fully internalizes life-cycle costs, but does not

consider the consumer benefits derived from improved service quality. If the effect on life-cycle

costs is positive (i.e. costs decline), then certainly some cost-reducing investment will be made, 

up to the point where the marginal cost savings equals the firm’s marginal investment cost, with 

all benefits accruing entirely to the private partner.48 Again, the investment level will be too low 

because the private partner does not consider the incremental benefit to consumers that would 

arise from making additional cost-cutting investments that also improve service quality. In other 

words, investment is too low compared to the socially optimal amount (the joint marginal benefit 

of higher quality and lower cost is greater than the marginal investment cost). 

It is also possible that investment could be too high. For instance, conventional procurement is 

preferable if the main effect of a technical innovation would be to increase benefits to consumers 

while also increasing operational costs, because only the government would be willing to make 

the costly investment needed to enhance quality. In this situation, however, it would be 

incumbent on the public authority to ascertain whether the increase in quality was worth the 

added cost, to avoid the risk of making a socially wasteful overinvestment in quality. 

Conversely, only a PPP would be interested in making investments that reduced life-cycle costs 

 47 Improved quality increases the value of the infrastructure service to consumers, and as a result, they are willing to 

pay more for it; the private builder and public authority may then share the monetized value stemming from higher 

quality. This could be accomplished through a sharing rule (say 50/50) incorporated into the contract, which is 

triggered only after the investment is made and its value realized (in other words, the value of the investment cannot 

be put into the contract because it is not known beforehand, but a sharing rule can be applied after the investment is 

made and its value quantified). In this scenario, the private builder has an incentive to underinvest because it knows 

in advance that it will receive only a portion of the incremental value; this is in addition to the underinvestment that 

occurs by not taking life-cycle cost savings into account. Having a preset rule in place may be preferable to waiting 

until after the investment is made before negotiating a sharing arrangement with the public sponsor; the added 

uncertainty could exacerbate the incentive to underinvest. 48 Absent other controlling contract provisions, the private partner in a PPP can unilaterally implement cost-cutting 

innovations and retain all of the benefits.
22

that also lowered service quality (the public authority would not take any actions that reduced 

quality). It would be important for the PPP to internalize the spillover effects of its investment 

decision, to avoid making a socially wasteful overinvestment in cost cutting that inordinately 

reduces quality. Yet if quality is contractible, this likely would not be an issue, and if quality 

was not contractible, then the public sponsor should probably opt for conventional procurement 

if cost-cutting leads to quality reductions (see discussion in section III).

Of course, if life-cycle costs are not very sensitive to quality-enhancing investment, so that the 

value of any quality enhancement would likely exceed the cost of the investment, then 

conventional procurement is likely preferable because the private partner in a PPP would not 

have the incentive to undertake this investment. In other words, a PPP would not be willing to 

make quality-enhancing investments that did not also reduce life-cycle costs (by more than the 

cost of the investment). 

Incentives can be used to encourage socially beneficial non-contractible investments and 

discourage non-contractible investments that are socially wasteful. 

A system of rewards and penalties can be used to steer the level of investment toward the 

socially optimal level. Performance-based contracts in which the PPP’s compensation is tied to 

achieving measurable output or quality outcomes can compensate for investment shortfalls by 

providing a monetary incentive to undertake additional quality-enhancing non-contractible 

investment that also reduce life-cycle cost. Similarly, penalties that reduce compensation for 

failing to achieve or maintain service performance targets can discourage socially wasteful cost 

cutting that otherwise would lead to excessive reductions in quality.