Sustainable Transportation for the Climate: How Do Transportation Firms Engage in Cooperative Public-Private Partnerships?

Abstract

This research examines the effectiveness of transportation-sector public-private partnerships (PPPs). Coordination across sectors is needed to reduce transportation-related greenhouse gas emissions. PPPs are of interest to transportation firms, but they may prefer private-sector opportunities given that working with the public sector can present challenges. However, the challenges are not clear and, therefore, this needs research investigation to develop understandings for policy to make PPPs work better for firms. Moreover, this research informs firms so that they may better comprehend and manage the risks of PPPs or choose other opportunities. This empirical research uses a sample of 300 transportation firms across 28 countries. The findings suggest that, although government contracts may be lucrative, the institutional environment of the PPP context is not preferable to other business-oriented private-sector opportunities. If more sustainable transportation is to be constructed to address climate change and other public interests, policymakers may need to rethink PPPs to adapt to the needs of transportation firms.

1. Introduction

This study sheds light on transportation firms’ experiences in public-private partnerships (PPPs) as compared to vibrant private-sector environments with an aim to determine how PPPs may affect firm outcomes [1,2]. Previous research defines PPPs as institutions made up of partnering organizations from the public and private sectors [3,4,5]. The perspective of the transportation firms is important to understand because if PPPs are not conducive to their success, then public-interest projects, such as those aimed at reducing transportation-caused greenhouse gas reductions, may not proceed as planned; firms may reject the offers or require higher payments to engage in the projects. Not having addressed this issue before, this study investigates whether firms find more success in business-friendly environments or in public-private partnerships (PPPs). The interrelated research questions of this study are: (1) Does a transportation firm benefit from a business-oriented national cultural context? (2) Does a transportation firm benefit by engaging in PPPs? (3) Does and how does a firm’s context, that being from a more business-oriented national culture, affect its success in a PPP? By understanding how to better manage PPPs so that firms find success in them, transportation firms and public institutions may work smarter together to realize the United Nations Sustainable Development Goals (UN SDGs) such as climate action (the thirteenth goal) and “Partnerships for the Goals” (the seventeenth goal) [6]. Sustainable, equitable transportation systems improve urban economies [1,7] so this research also supports goals nine, eleven, and twelve, relating to infrastructure, cities, and responsible production and consumption, respectively [6].

The research complements existing transportation policy investigations where the closest related work is a study by [8] examining the effects of institutional factors on the success of PPPs in ports, published in Transportation Research Part A: Policy and Practice. Thus, the current study builds on previous research finding that institutional factors including regulatory quality, market openness, ease to start a business, and contract enforcement are determinants of the success of transportation projects [8]. The current study adds national culture to the list of factors to consider and examines contextual differences and consequences for transportation firms working outside or inside PPPs. The additional factor is justified by an abundance of recent transportation research recognizing cultural context as important for policy [2,7,9]. Recent transportation research has recognized cultural contextual influences including values and the importance of cooperation for the workability of transportation projects [7,9,10]. This study adds to this recent research interest by combining cultural influences and cooperation to make some theoretical predictions and offer empirical evidence for transportation firms in PPPs.

This international study makes theoretical, policy, and empirical contributions to PPP transportation research through an institutional theory lens, in line with other PPP literature [11]. Culture in a general sense has been part of institutional theory as an institutional pressure [12,13,14]. Yet research has paid only some attention, for example, in the international corporate governance literature, so this research expands on how national culture acts within institutions [15,16]. Other scholars agree that national cultural values influence the design and operation of institutions, thus there is plenty of justification for testing how national culture and the PPP context might interact [2,17,18].

To test the theory, the study uses an international sample of 300 transportation firms across 28 countries in regression analyses. Transportation firms working with the public sector in PPPs offer cities positive economic impacts as innovative employers improving urban infrastructure [19]. Thus, the effects on transportation firms in this study are related to their employment numbers as a dependent variable, of primary interest to both firms and policymakers. A financially thriving firm expands and develops stronger capabilities to build infrastructure as it takes on more and/or larger projects, and thus hires more workers who also benefit from the skills development. Recognizing that the firms must be financially stable [20,21,22], the mutually interesting outcome is employment for the private and public sectors in PPPs. Moreover, by using a performance measure such as the size of the firm as an outcome variable, this work informs firms as to whether and when PPPs are beneficial for them.

The next section is a literature review with development of hypotheses. Then, a methods section describes how the hypotheses are tested. Results are presented, followed by discussion and conclusions to sum up the research and suggest future directions.

2. Literature Review and Hypotheses

This section reviews research, relevant to transportation firms, to explain how the current study adds to existing understandings in the PPP literature using an institutional theory lens. Institutional theory considers mechanisms leading to isomorphism of institutions such as cultural-cognitive, normative, and regulative pressures [13,14]. These isomorphic pressures cause institutions and supporting organizations to become similar. According to this well-established theory, isomorphism builds legitimacy, enabling conforming institutions and organizations to attract resources [14,23]. For example, transportation research has explained that a private sector firm likes to work with a public partner due to the legitimacy conferred on a project helping the private partner manage its risk [10]. The current study extends early conversations in institutional theory oriented to culture by examining how national culture and institutional pressures, derived from legitimizing isomorphic PPPs, may interact to affect the firms participating in those contexts. Some previous research has also combined these concepts. Drawing upon institutional theory, [24] theorize without empirical evidence that individual organizations may be influenced by the national culture in which they are embedded, as could be the transportation firms in this study. However, their work does not accept that national culture predictably affects organizations as contexts change. They consider different outcomes for organizations based on varying national cultural environments and characteristics of the organizations. Their variables and context differ from the current research, but their work uniquely and conceptually sets the stage for this research positing that a national culture could clash with an institutional context.

Other studies that focus on integrating national culture into institutional theory are few [25]. Previous research has noted that institutional theory considers cultural-cognitive elements as influencing emerging and persistent aspects of institutions [25,26]. The relationship between national culture and corporate reputation has been researched where national culture was considered an informal aspect [27]. Otherwise, some research discusses national culture in terms of institutional logics [28]. According to that research, institutional logics incorporate national culture because institutional logics are composed of material practices and symbolic systems, the latter being culture, including national culture [28,29,30]. Whereas that research combines culture and material practices within institutions to explain how they work, this research considers national culture as a congruent pressure on firms entering an incongruent institutional context such that the national culture may not be helpful to the firm while in the PPP [28]. In some ways, this could be considered a study of contradictory institutional logics [31,32,33]. For example, [27] consider national culture to be an informal institution. This view would be consistent with this research because national culture, viewed as an informal institution, influences firms within the nation. GLOBE researchers state that they considered both values and practices to arrive at the societal cultural dimensions [34]. Thus, the GLOBE study national cultural dimensions could reflect a national institutional logic. Therefore, this study examines the impact on transportation firms when a national institutional logic collides with the institutional logic of a PPP. Corporate governance literature has also explored how culture could affect corporate institutions, tending to assume congruence with a national environment.

In general, corporate governance literature has discussed national culture as reflected by institutions, and the following reviews some key studies and findings, explaining how the current research differs. For example, ref. [16] note that governance structures are different depending on national cultures. Germany has two-tiered boards that increase participation and transparency, whereas insiders control boards in Japan and in the United States, boards have a mix of insiders and outsiders [35,36]. Research finds that a nation’s sociocultural characteristics affect the choice of board structure [16]. Accordingly, that research describes organizations “as social entities integrated into the institutional and value structures constituting the culture of a society [37]” [16] (p. 611). While results correspond to their description of organizations, such that national culture is directly reflected in governance structures, that research did not develop institutional theory or consider the consequences on any firm outcomes. In contrast, the current research develops institutional theory by considering the effects of interactions of national culture and involvement in PPPs on an outcome variable for a firm, its size, thereby considering the consequences for firms. The previous research was concerned with the impact on an internal institutional structural variable. Instead, this research sees the firm enter into an external institution with other partners, including the public service in a PPP. Thus, this research considers whether a business-oriented national culture, normally supporting the firm, can still operate supportively within the PPP, or whether the PPP’s conditions predominate over the national culture influence, arriving with the firm.

Research on corporate governance incorporating culture by [15] examines corporate practices rather than structures as outcomes. That empirical investigation finds that GLOBE national cultural dimensions influence the institutional environment as a mediator that then influences corporate governance practices. In that research, national culture also affects governance practices directly, in conformance with other previous research [38], but their main interest was to show the mediating relationship [15]. In contrast, the current research focuses on governance through PPPs as an interacting factor with national culture affecting firms’ performance, rather than considering corporate governance as an outcome. From a transportation firm’s perspective, performance information is more useful for indicating which types of projects to choose.

2.1. Business-Oriented National Culture May Facilitate Firms

Having explained the rationale, this study first proposes a positive relationship between a business-oriented context and firm performance to establish whether the national cultural variables affect firm outcomes. A performance-oriented national context may align well with a firm’s performance orientation, thus supporting its success rather than working against it. However, the following discussion explains that this relationship may not be as straightforward as it seems, partly because the performance orientations may need to be aligned by similar goals [39]. Moreover, a firm may not strongly internally align to its own stated purpose, thus making it difficult to find a consistent correspondence with any external context because the firm is not consistent within itself.

Some previous research suggests that business orientation, assertiveness, and performance-oriented culture could be facilitative of firms [40]. In business research, firms are often viewed as performance-oriented, meaning that they reward performance improvement and excellence, but this assumes that firms’ goals are well-defined while internal constituents’ interests and reward systems are aligned [41,42]. A common view in business is that a for-profit organization has the advantage of a singular clarifying direction, that being the profit goal [41]. In comparison, government and civil society have multiple goals oriented toward the public interest that make performance harder to define [39].

Not all literature agrees that firms are as clearly goal-oriented as some believe though, even opposing the view, such that a firm is composed of competing interests [26,43]. Competing interests can result in shifting goals so that what is rewarded as “performance” becomes less clear [39]. Furthermore, research discusses sustainable firms such that they pay attention to the triple-bottom-line [44]. While they are profit-oriented, the profit is calculated after including social and environmental costs or externalities generated by the firm. Moreover, a firm using the triple-bottom line could have environmental and social goals to create positive externalities, in addition to profit. Thus, the for-profit firm, traditionally discussed as performance-oriented because of its clear profit goal, may be too simplistic for reality [41,45,46].

However, one could argue that if a firm’s core business is sustainability, as is the case for many transportation firms today, then performance could be defined by profit. The firm earns profit by solving the world’s problems such that its inherent business model, which leads to profit, is to create positive externalities for society [47,48,49]. This view is implied in the introduction, where, for example, transportation firms reduce greenhouse gas emissions by building electrified mass transit, and more broadly, as outlined by the UN SDGs and espoused by the UN Global Compact [50,51]. In this view, the firm defines its performance orientation towards achieving a business purpose rather than a financial purpose [52,53]. The firm creates a business model to achieve the business purpose, measured financially. Thus, profit is not the sole goal. Instead, achieving the business purpose of, for example, supplying a city with electrified train cars while the firm remains viable (profitability is necessary for reinvestment to maintain and upgrade capabilities), is the goal. How a firm achieves profit is the goal. Thus, profit is not necessarily the best performance measure because a transportation firm that makes profit the absolute priority might then take projects that do not fit its strategy or purpose [54]. Therefore, an outcome measure like profit would not indicate firm performance based on its purpose.

Furthermore, the performance orientation of the nation may not be aligned to any firm goals, profit or otherwise. Under realistic circumstances, a performance-orientated national culture may not have any relevance for firms because the nation has different goals than those of its firms [39]. Rather than making profit or revenues the performance measure for this study, a measure aligning with policy interests is chosen, the size of the firm by employee numbers. This measure only somewhat indicates whether the firm is achieving its business purpose, as it uses its own staff rather than relying on temporary outsourcing. However, the size by employee number suggests the firm is remaining viable, because it can pay its staff, and aligns a firm with the goals of policymakers, and possibly then, a national culture’s performance orientation. A nation desires high performance for a competitive economy [55]. A transportation firm wants to build transportation systems while remaining a going concern and, from the policymaker’s perspective, it does this by offering employment opportunities that benefit local economies [56]. Thus, the following hypothesis relates the national performance orientation to firm size based on the number it employs.

H1a. 

As the performance orientation of a national culture increases, the size of the firm in terms of number of employees increases.

The GLOBE variables of this research, performance orientation and assertiveness, were chosen with an understanding that, while they are both business-oriented values, they were also found to be in different components based on a principle components analysis in [15]’s research. In that research, they defined a new combined (or latent) variable composed of uncertainty avoidance, power distance, performance orientation, and future orientation that they called “national economic culture.” So, that work seems to agree that performance orientation, as part of the larger economic component variable, relates to business. Ref. [15] did not explain the rationale for why assertiveness would not be part of their “national economic culture” variable. Therefore, it will be of additional interest in this research to see whether different results are found with the two cultural dimensions, performance orientation and assertiveness, in accordance with [15]’s principle component analysis. This research uses a different analytical approach, but it may triangulate some of the previous work’s inferences in terms of the differences between the two national cultural dimensions.

Other research does justify assertiveness as a business-oriented cultural dimension [40]. Ref. [40] use the GLOBE dimension, assertiveness, at the national level of analysis. Ref. [40] consider culture as a moderator for the innovation—growth relationship, in their entrepreneurship research. Their study defines innovation as including the successful introduction of new products/services, supply and production methods, markets, and the new organization of industries [57]. This previous research uses the size of the firm as part of a performance measure. Ref. [40] predict a lower assertiveness orientation enhances the innovation-growth relationship. They believe that a national culture of assertiveness could inhibit the deployment of innovation due to heightened competitive activity.

Most theory suggests that innovation thrives in a competitive environment [42,58]. However, ref. [40] explain that not much prior research has used the GLOBE assertiveness variable, instead discussing characteristics of business culture such as competitiveness, rather than using national culture dimensions. For example, both works by [42,58] examine entrepreneurial orientation (EO) at the firm level. In the earlier article [42], they tie EO to performance and suggest that competitive aggressiveness is a driving force, not destructive of motivating innovation. The later article examines proactiveness and competitive aggressiveness as two distinct aspects of EO [58]. That work suggests that competitive aggressiveness is an orientation helpful to firms in the mature stage of their life cycle. In line with life-cycle stage considerations, some previous entrepreneurship research implies that performance-focused and assertive cultures may hold back small firms needing social capital support [59]; thus, larger firms may benefit under these circumstances.

More recently, ref. [60] specifically tested the assertiveness orientation variable from GLOBE and found that it has no effect, instead stating that, “Perhaps, assertiveness does not moderate the EO–performance relationship because internal conflict can also be a source of creativity and innovation [61], strengthening the implementation of EO” [60] (p. 282). In contrast, ref. [62] directly ties innovation to aggressiveness. In light of the past confusion, but on balance, more positive expectations for assertiveness, this research tests a positive relationship for assertiveness on firm performance. The following hypothesis proposes that assertiveness is a business-oriented national culture variable expected to support firm performance.

H1b. 

As the assertive orientation of a national culture increases, the size of the firm in terms of the number of employees increases.

2.2. Public-Private Partnerships May Support Larger Firm Size

Next, transportation PPPs are proposed as beneficial for transportation firms. PPPs have become conventional practice since the 1980s in most countries, whether developed or not, and are numbered in the thousands around the world representing billions of dollars in spending [19,39,63]. These partnerships are lucrative business opportunities on large-scale projects giving the firms longer-term stable government contracts [19]. On acquiring one or more PPP projects, firms will need to staff them, and either they must hire more expertise or they already have it. Thus, transportation firms engaged in PPPs are expected to be larger by employee numbers. As long as they continue to be able to pay larger staffs, they are considered more successful going concerns.

However, the expectation of the aforementioned conceptual linkage may be argued such that the risks a firm accepts in a capital-intensive transportation PPP may not lead to its success, and may even lead to its ruin instead [10,63]. For example, ref. [63] describes a Thai case in which the Bangkok Expressway Company Ltd. (BECL) went into bankruptcy after public and other external lobbies demanded and won a lower toll on a highway project. Other literature has discussed these types of political risks including the need for political backing of projects, especially where foreign corporations are invited and public sentiment shifts with changeovers of government [64]. Governments choose the fully integrated PPP structure, where their private partner holds a lease on an asset that it designs, builds, finances, operates, and maintains (DBFOM). The government thereby transfers several types of risk to firms such as financial risk, the risk of cost overruns, construction risk (e.g., delays in project completion), and availability risk (e.g., poor service delivery) over twenty to fifty years [65]. Ref. [63] systematically explains four kinds of risk in transport investments: (1) technical risks (risks in construction, design, or specifications) such that actual costs of projects are about 28% higher than projected, on average; (2) commercial risks, for example, overestimations of transport demand and the immobility/inflexibility of transport assets; (3) political and regulatory risks; and (4) economic and financial risks as related to macroeconomic conditions and local issues such as restrictions on foreign currency exchange. Over the decades-long period that the private partner is involved, it must recover its upfront costs and make a profit [63]. In a PPP, a firm facing problems with its project would find that transportation infrastructure is difficult to exit [63]. The public sector takes ownership of the asset only after the contract period. In the past, the public sector would accept all of the risk, overseeing the contracts for each part of a project, financing it, and keeping the asset on its balance sheet [65].

Moreover, one could argue that these partnerships are not necessarily the best mode for governments either, if they are focused on the long-term public interest from a comprehensive standpoint [1,7]. Meanwhile, firms could experience negative consequences involved in servicing these interests, so PPPs seem to have problems for all parties. Some literature states that it is an ideological position to believe that the private sector can deliver better than can the public sector on infrastructure [64,66]. Politicians are reducing their own political risk while focusing on the most expedient solutions as related to cost-effectiveness [65,66]. The literature has argued that whether PPPs actually generate value for money is debatable because much of the argument for them is based on a transfer of risks, having a value hard to estimate [67]. Research examining three transportation PPP case studies around the world in the UK, USA, and Australia suggests that failed PPPs can leave governments with increased risk [19]. Governments sacrifice other long-term public goods associated with more holistic solutions [65]. For example, social capital building through place-making, design, and beautification is missed [68,69,70]. Then, serious public issues arise later, and politicians deal with the accumulating fallout, such as congestion, social problems, and even crime [71]. At the same time, the literature also recognizes that the global challenges of today, including those related to the United Nations Sustainable Development Goals, require cross-sector and international coordination [66]. The private sector can bring specialized expertise to bear such as in financing (e.g., private long-term debt financing), innovation and technology, and management [64,65]. So, the PPP is a tool that may support societal goals, depending on how the involved parties engage in it [66].

This intensive partnership approach remains complex because it requires “collaborative public management” [72]. Collaborative public management involves many organizations applying diverse sets of expertise to colabour and boundary span to reach common goals [72,73]. This involves reciprocity and public engagement such that key external players may both contribute to and suddenly interfere in projects [39,72,73]. The public and private sectors also have different sets of conflicting priorities and values where, for example, the public sector may strive to avoid trade and commerce while preferring hierarchy and loyalty, whereas the private sector may enjoy competitiveness and voluntary agreements [39]. Thus, coordination of these partnerships, balancing high levels of interdependence with autonomy while attempting to reach consensus and maintaining public accountability can be challenging [64,74]. Case study research finds that joint fact-finding works in the earlier stages, but that later sharing of responsibilities is not practical, partly because individual organizations must deal with their own internal issues [39]. Thus, there is a reversion to a network form dominated by bilateral contracting and separated responsibilities [39].

When long-term PPP contracts are accepted, they are often subject to habitual renegotiations (or “compensation events”) and even lawsuits, adding costs and causing work interruptions [67]. In anticipation of issues in PPPs, firms demand non-competition clauses in the PPP agreements [19]. Moreover, the private sector is not habitually as transparent to local communities affected by these sometimes-clandestine PPP agreements, as was vehemently discussed in relation to Alphabet’s (Sidewalk Lab’s) unclear plans for Toronto’s waterfront [19,75]. Partnership difficulties arise later when governments are hemmed in by those restrictive PPP clauses that block required new infrastructure as cities grow and change [19]. When governments win the lawsuits, this can leave the firms and their projects in financial difficulty, but these fights can also be costly for the public sector [19]. The Eglinton Crosstown light rail project in Toronto, now having its completion date delayed by a year and a potential lawsuit in progress, is a recent example [67,76].

Overall, ref. [66] explain that if PPPs are to result in public benefits, then partner behaviors must align with the principles and practices of good governance. The literature recognizes that there are three types of controls to ensure public accountability, including accountability: (1) through hierarchy, (2) through multiple governmental bodies, and (3) through objective standards [64]. In the UK, the National Audit Office evaluates partnership success prior to completion by doing audits of in-process projects. They compare past performance, performance by others, and performance standards as set out in the PPP agreements [64].

Although the literature discusses many of the pitfalls of PPPs, the evidence suggests that these collaborative institutions do lead to positive results for firms, or else PPPs would not continue to exist [39,65,72]. Firms would not continue to be involved if the track record, over thousands of these projects around the world, were not lucrative [77]. The literature argues that PPP processes are improving through experience resulting in increased levels of success [78]. Firms having more experience in PPPs are able to manage the risks and gain from them [77]. Research explains that PPPs require rare and special expertise, combined with sufficient resources, so the same firms having these attributes will repeatedly obtain the PPP work [39,64,77]. These PPP firms also must have a correspondingly larger workforce and thus, firms involved in more PPPs are expected to be larger. The following hypotheses reflect the previous discussion and expectations that PPP firms will tend to find success through PPPs reflected in their larger size.

H2a. 

If a firm has a PPP, then the size of that transportation firm, measured by number of employees, will be larger.

H2b. 

The more PPPs that a firm has engaged in, the larger the firm in terms of number of employees.

2.3. Business-Oriented National Culture May Not Facilitate Firms in Public-Private Partnerships

The following questions have been considered separately: (1) whether expectedly business-oriented GLOBE national culture dimensions, performance orientation and assertiveness, support a transportation firm; and (2) whether PPP projects are beneficial for an involved transportation firm, despite the many pitfalls of PPPs. This section predicts that, although these separate relationships are expected to have positive outcomes for firms, the combination of these factors will not be supportive for the firms. The main reason is that, as explained already in depth, PPPs require collaborative behavior to support the interdependence of the partners [72,77]. As the previous PPP literature has explained, the interdependent coordination is complex in itself. Furthermore, previously cited case study research has found that only bilateral relationships are manageable because each organization is dealing with its own set of internal issues together with the external relationship [39]. PPP relationships tend to deteriorate into contractual relationships [39]. Given the special expertise and resources required for PPPs, a limited set of partners can engage in them so this also leads to opportunistic behavior, according to previous research [39,64].

In combining the aforementioned factors, whether having a performance orientation or a general tendency towards assertiveness within PPPs, the literature has found that these factors do not facilitate innovation and the development of high-quality products [39]. However, the two dimensions are different where, according to the definition of performance orientation, it lends itself to the group dynamic, towards performance improvement and excellence. In contrast, assertiveness is a more individualistic and aggressive trait [34]. Performance orientation may seem an aspirational ideal for a PPP, and in practice, partners’ goal alignment is shaky, as expressed by existing literature discussing the different values held by the public and private sectors [39]. Seminal organizational theory has well established the differing interests of actors within the same organization [26] and other research has considered the challenges of cross-sector cooperation [79]. Moreover, if the GLOBE version of assertiveness describes a more confrontational and aggressive orientation [34], then it is similar in description to the aforementioned opportunistic forces described in the PPP literature related to PPP problems, not their success. In sum, the business-oriented national culture factors and PPPs do not mix well, so the following hypotheses predict smaller firms as outcomes under these circumstances, whether having had only one or more PPPs. The requirement of a collaborative culture for PPP success is expected to override what would otherwise be the benefits derived from a competitive business-oriented national environment.

H3a. 

A firm from a higher assertive orientation national culture and also in a PPP will have a smaller firm size in terms of its number of employees.

H3b. 

A firm from a higher performance orientation national culture and also in a PPP will have a smaller firm size in terms of its number of employees.

H3c. 

A firm from a higher assertive orientation national culture and in a higher number of PPPs will have a smaller firm size in terms of its number of employees.

H3d. 

A firm from a higher performance orientation national culture and in a higher number of PPPs will have a smaller firm size in terms of its number of employees.

3. Research Methodology

The following section describes the data and sample selection for examining the hypothesized relationships. The section begins by describing the data used, the main variables of interest, the controls, and the statistical methods.

3.1. Data and Variables

The empirical analysis draws upon an international sample of the top-ranked 300 transportation firms listed in Crunchbase, so they are more likely to have been involved in PPPs. The rank suggests the sample of firms has a lot of activity and compares well to peers, so they are more likely to be in PPPs. At the same time, the choice does not rely on the size of the firm or typical financial indicators, so the sample has the potential for a good mix of characteristics. Ref. [80] explains online that:

Crunchbase Rank is determined by an algorithm that takes into account the number of connections of a profile within the platform, the amount of community engagement, funding events, news articles, acquisitions, and more. These factors decay over time at varying rates depending on the factor (i.e., news decays more quickly than size of funding rounds)… The benefit of Crunchbase Rank is it lets users prioritize their search results by influence. The higher the Rank, the more influential the profile is compared to its peers.

The transportation PPP setting is opportune for this investigation because transportation firms are often private, but they work on public infrastructure with public institutions interwoven [81]. The sample of transportation firms is in 28 countries/regions across continents (See

Table 1. Sample Statistics—Companies by Country.

Country	No. of Companies	No. of Sustainable Companies
Australia	2	2
Brazil	2	0
Canada (English-speaking)	6	4
China	4	2
England	15	11
Finland	1	0
France	6	0
Germany (EAST)	1	1
Germany (WEST)	4	3
Greece	1	1
Hong Kong	1	0
India	14	5
Ireland	1	1
Israel	10	2
Italy	3	0
Malaysia	1	0
Mexico	4	4
Netherlands	4	4
New Zealand	3	2
Portugal	3	3
Russia	2	0
South Africa	1	0
South Korea	1	0
Spain	3	3
Sweden	6	5
Switzerland	5	3
USA	196	94
Grand Total	300	150

, below). Crunchbase has a search engine that extensively categorizes and ranks firms, which is convenient for research samples where defining the industry and choosing a set of firms as objectively as possible is important in this case, transportation firms. Many firms cross industry boundaries, and a search engine with predefined categories can objectively resolve this categorization challenge. The sample firms are varied by subtype and are not subcategorized more finely by Crunchbase beyond being transportation firms. The aim of the research is to examine firm experiences in transportation PPPs for more generalizable learning given transportation PPPs are a significant part of PPPs overall (and cleaner transportation across all categories is consequential for climate change) [82]. Crunchbase has been justified in prior research for similar types of quantitative and/or large empirical analyses [83,84]. Ref. [83] (p. 20) state that the quality of Crunchbase data has been thoroughly tested. Furthermore, Crunchbase offers an extensive database of private and public organizations at various stages of development and includes a variety of investment information and the size of the firms. Private firms do not report financial information publicly so the size of firm based on revenues cannot be collected, but Crunchbase offers the advantage that it does collect size-of-firm information based on ranges of the number of employees.

The dependent variable in this study is the size of a transportation firm, based on its number of employees, as shown in the hypothesized relationships of Figure 1. The Number of Employees is a discrete variable representing the size of each firm in the sample based on Crunchbase ranges of total employees in a firm (Please see

Table 2. Summary list of variables and sources.

Variable	Description	Source
Number of Employees	This is a discrete variable representing the size of each firm in the sample.	[40,80]
Performance Orientation Societal Values	The degree to which a collective encourages and rewards (and should encourage and reward) group members for performance improvement and excellence.” [34]	[15,34,85]
Assertiveness Societal Values	The degree to which individuals are (and should be) assertive, confrontational, and aggressive in their relationship with others.” [34]	[15,34,85]
PPP	This variable expresses whether a firm has had at least one public-private partnership (PPP) (coded 1) or not (coded 0).	Firm and government websites
Number of PPPs	This is a count variable of the number of PPPs a firm has had.	Firm and government websites
Firm Age	The number of years the company has been in business.	[80,86]
Total Funding Amount	The total amount of equity funds the firm has raised over its lifetime, in US dollars.	[80]
Country Dummy	Control for all other national factors aside from the cultural dimensions explicitly included as independent variables.	[86]

for a summary list of variables). This variable has a countable number of ranges from 1 to 9 so it is discrete. For example, a firm with 1–10 employees was assigned a 0, a firm with 11–50 employees was assigned a 1, and so on (51–100 is 2, 101–250 is 3, 251–500 is 4, 501–1000 is 5, 1001 to 5000 is 6, 5001 to 10,000 is 7, 10,001+ is 8), so that as a firm fell into a category representing a larger number of employees, it was assigned a higher number. From

Table 3. Basic Statistics.

Variables	N	Mean	Sd	Min	Max
Firm Age	300	9.74	15.48	0	147
Firm Size Category	300	1.13	1.76	0	8
Total Funding Amount	300	9.76 × 107	7.48 × 108	0	1.16 × 1010
PPP	300	0.19	0.39	0	1
Number of PPPs	300	0.40	1.18	0	10
Performance Orientation Societal Values	300	6.05	0.18	4.92	6.40
Assertiveness Societal Values	300	4.15	0.43	2.83	5.44

, one can see that this size ranges from 0 to 8. The size of the firm was not available in revenue dollars because many firms are not public and therefore do not report this information, but the number of employees is another approach to measure the size of the firm. In the case of PPPs, a workforce size variable is a better reflection of success than a single financial measure, indicating that the firm can afford to keep more employees on its payroll in addition to its other required expenses. Additional rationale for choosing workforce size is included with the hypotheses, above. Government policy for PPPs is often concerned with creating employment, and other studies have used employment-related dependent variables [40].

Cultural dimension coding by country used for the independent variables, Performance Orientation Societal Values and Assertiveness Societal Values, is sourced from the GLOBE data developed by [34]. The GLOBE study is an evolved and improved version of [85]’s earlier work, having nine dimensions instead of five [15,34,85]. The GLOBE study is quite thorough, having established the theoretically supported cultural dimensions with the aid of 170 researchers across 62 countries who collected data from approximately 17,000 participants representing 951 businesses. As explained earlier, the two dimensions of this study have been justified as business-oriented in previous research.

PPP data produce two PPP independent variables; one is a dichotomous variable called “PPP” to express whether a firm has had at least one PPP (coded 1) or not (coded 0). The other PPP variable is a count of the number of PPPs a firm has had, called “Number of PPPs.” The data come from a systematic two-step online search process: (1) an extensive search of company websites including press releases, announcements, and blog postings; and (2) two Google searches where the first three pages of results are reviewed. The two searches included the company name with the phrase “public-private partnership” and the company name with the phrase “public-partnership”. Since public-private partnerships are inherently public knowledge and therefore not secrets, both private and publicly traded firms report all of their PPP engagements as positive information to investors because they have won business.

Control variables were considered for this research on logical, theoretical, and empirical bases from previous studies. The age of each firm in years, Firm Age, was collected from Crunchbase and included because a firm could be larger if it is older, as it has had more time to develop. Moreover, the total amount of equity funds the firm has raised over its lifetime, in US dollars, is a variable called Total Funding Amount, comprised of data collected from Crunchbase. This variable is included because funding is a potential monetary indicator of success, early attractiveness to investors, and potential success where revenues and other financial data are not available for private firms. However, a firm could become successful without ever having received external funding. Moreover, it is typically growth-oriented small to medium-sized firms that report this funding information, so this variable would favor them over more mature firms that could actually be more successful than their younger counterparts. Thus, funding is a useful control but would not be considered a dependent variable reflective of success. Additionally, a Country Dummy variable controls for all other national factors aside from the cultural dimensions explicitly included as independent variables. The Country Dummy and Firm Age variables are often used in empirical studies and are logically included in this analysis, as explained [86].

Basic statistics and correlations for all of the variables used in this research are in Table 3 and

Table 4. Pairwise Correlations.

	Firm Size Category	Firm Age	Total Funding Amount	PPP	Number of PPPs	Performance Orientation Societal Values	Assertiveness Societal Values	Country Dummy
Firm Size Category	1
Firm Age	0.19	1
Total Funding Amount	0.35	0.01	1
PPP	0.35	0.07	0.19	1
Number of PPPs	0.40	0.13	0.43	0.71	1
Performance Orientation Societal Values	−0.13	0.03	0.02	0.01	−0.04	1
Assertiveness Societal Values	0.18	0.08	0.08	0.07	0.07	0.48	1
Country Dummy	−0.02	0.04	0.03	0.06	0.05	0.48	0.34	1

, respectively. The basic statistics in Table 3 show that most firms in the sample are smaller and about ten years old, but there is wide variation on both dimensions. Moreover, about 19% of the firms in the sample have had at least one PPP. The performance orientation (mean is about 6) and assertiveness (mean is about 4) of the national cultures of countries in which the firms have head offices are on average around the middle of a ten-point scale, where none of the national cultures reaches very high values on either cultural dimension. Given these statistics, it is doubtful that there are extreme outliers that would bias results.

In Table 4, the Assertiveness Societal Values and Performance Orientation Societal Values variables are somewhat correlated at 0.48 so interactions involving these variables are separated in the regression models to avoid the collinearity, recognizing that country factors are generally controlled for with the Country Dummy. Additionally, in Table 4, the Total Funding Amount and Number of PPPs variables are only moderately correlated at 0.43, and this is not expected to be a concern. In addition, the PPP and Number of PPPs variables are correlated at 0.71, but this is to be expected and is somewhat of a good result from a consistency point of view, because they are both supposed to measure the extent of involvement in PPPs in slightly different ways.

3.2. Methods

Overdispersion in the dependent variable, Number of Employees, suggests a negative binomial model, where the variance is much greater than the mean [87]. All models in

Table 5. Model Results with the Dependent Variable Firm Size Category.

	(1)	(2)	(3)	(4)	(5)
Firm Age	0.02 ***	0.02 ***	0.02 ***	0.02 ***	0.02 ***
	(−0.01)	(−0.01)	(−0.01)	(−0.01)	(−0.01)
Total Funding Amount	0.00 **	0.00 ***	0.00 ***	0.00 **	0.00 *
	(0.00)	(0.00)	(0.00)	(0.00)	(0.00)
PPP	0.82 ***	14.64 ***	0.79 ***	4.82 ***	0.71 ***
	(−0.22)	(−4.98)	(−0.23)	(−1.48)	(−0.24)
Number of PPPs	0.01	−0.01	2.96 **	0.07	1.04 **
	(−0.07)	(−0.08)	(−1.28)	(−0.07)	(−0.42)
Performance Orientation Societal Values	−1.57 ***	0.10	−0.16
	(−0.49)	(−0.58)	(−0.54)
Assertiveness Societal Values	0.73 ***			0.86 ***	0.75 ***
	(−0.19)			(−0.22)	(−0.20)
Country Dummy	0.00	−0.00	−0.00	−0.01	−0.02 *
	(−0.01)	(−0.01)	(−0.01)	(−0.01)	(−0.01)
Performance Orientation Societal Values × PPP		−2.29 ***
		(−0.82)
Performance Orientation Societal Values × Number of PPPs			−0.49 **
			(−0.21)
Assertiveness Societal Values × PPP				−0.96 ***
				(−0.35)
Assertiveness Societal Values × Number of PPPs					−0.22 **
					(−0.09)
Constant	6.01 **	−0.94	0.63	−3.65 ***	−3.15 ***
	(−2.62)	(−3.38)	(−3.17)	(−0.92)	(−0.84)
Number of Observations	300	300	300	300	300
Standard errors in parentheses	*** p < 0.01, ** p < 0.05, * p < 0.1

use a negative binomial model.

Moreover, a hierarchical regression approach is used such that control variables are modeled first, then main effects are added, and finally interactions are added [88]. The results are discussed below with the analyses in Table 5.

In addition, the direction of causality is further discussed here. First, the size of a particular firm today would not cause a particular characteristic of a national culture such as a performance or assertive orientation developed over time [34,89]. Nor would the size of the firm today, based on number of employees, cause a PPP to happen or cause several PPPs over the firm’s past history. Lagged variables are often used when there is a question about the direction of causality [90,91]. For this analysis, it is not possible to lag the PPP variables over the previous year or two because the firms would have had PPPs at widely different times in their histories. However, the Number of PPPs variable is like a lagged variable because it is the accumulation of these events over time prior to and up to the date when the size of the firm is measured. Similarly, the dichotomous PPP variable indicates the firm engaged in such an activity prior to or at the same time the size of the firm was reported. In any case, it is not the size of the firm that is relevant and instead, the age of the firm, possibly enabling it to accumulate more experience in PPPs as the aforementioned theory outlines, is the relevant control utilized in this analysis.

A negative binomial model takes the form of a probability mass function:

f(x) = (n + r − 1)C(r − 1) p^rq^x

where C is the combination formula (_nC_r = n!/(r!(n − r)!), x = 0, 1, 2 is a random variable, n is the number of independent trials, r is the number of successes, p is the probability of success, q is the probability of failure, and p + q =1.

The specific mathematical formulae representing the negative binomial models of main interest for this study are below.

(1)

Main Effects:

Number of Employees = exp(Intercept) × exp(b₁(Firm Age)) × exp(b₂(Total Funding Amount)) × exp(b₃(Country Dummy)) × exp(b₄(PPP)) × exp(b₅(Number of PPPs) × exp(b₆(Performance Orientation Societal Values) × exp(b7(Assertiveness Societal Values))

(2)

Interactions:

(a)

Number of Employees = exp(Intercept) × exp(b₁(Firm Age)) × exp(b₂(Total Funding Amount)) × exp(b₃(Country Dummy)) × exp(b₄(PPP)) × exp(b₅(Number of PPPs)* exp(b₆(Performance Orientation Societal Values) × exp(b₇(Assertiveness Societal Values)) × exp(b₈(PPP × Performance Orientation Societal Values)) × exp(b₉(Number of PPPs × Performance Orientation Societal Values)

(b)

Number of Employees = exp(Intercept) × exp(b₁(Firm Age)) × exp(b₂(Total Funding Amount)) × exp(b₃(Country Dummy)) × exp(b₄(PPP)) × exp(b₅(Number of PPPs) × exp(b₆(Performance Orientation Societal Values) × exp(b₇(Assertiveness Societal Values)) × exp(b₈(PPP × Assertiveness Societal Values) × exp(b₉(Number of PPPs × Assertiveness Societal Values))

4. Results

The analyses use a hierarchical regression approach, so first controls were tested on the dependent variable, Number of Employees. With only controls, the Firm Age and Total Funding Amount variables are significant, whereas the Country Dummy is not, and this is consistent across all the models in Table 5; therefore, this first basic model is not shown in Table 5 for brevity. For all models, the likelihood ratio tests that alpha equals zero–the likelihood ratio test comparing this model to a Poisson model, strongly suggests the negative binomial model is more appropriate than the Poisson model. In examining residuals, there were no obvious problems such as outliers. Moreover, the Wald chi-square statistic and p-value for the chi-square were checked. These latter statistics confirmed that the sets of independent variables were collectively statistically significant for all models.

The first model in Table 5 shows the results of regressing the controls and main effects on the dependent variable. This model tests H1a, H1b, H2a, and H2b. H1a is not supported and instead, performance orientation has a negative significant effect on firm size. At the p < 0.01 level, the coefficient on performance orientation is −1.57 and a possible explanation will be discussed in the next section, but this potential was foreshadowed in the hypotheses development section. H1b relates to the direct effect of a national assertive orientation on the size of the firm. In support of H1b, assertiveness is a supportive business-oriented national cultural characteristic, as it is positively and significantly related to the size of firm at the p < 0.01 level with a 0.73 coefficient. Next, H2a is supported where having at least one PPP positively and significantly relates to firm size at the p < 0.01 level with a coefficient of 0.82. However, having more PPPs in Model 1, as in H2b, does not predict any effect on firm size where there is no significant effect. In Models 3 and 5, the Number of PPPs is positive and significant, as predicted in H2b. These models contain the interactions of the national cultural variables with the Number of PPPs variable. While the changing results for the Number of PPPs (H2b) seems difficult to explain at first, the inconsistency across the models may relate to the fact that the PPP and Number of PPPs variables are somewhat correlated. When Model 1 is run without the dichotomous PPP variable included, the Number of PPPs variable is found to be positive and significant with a coefficient of about 0.2 with p < 0.01. This research will take this to mean that H2b is supported.

Models 2–5 in Table 5 address H3a, b, c, and d, which are the interactions separately examined due to potential collinearity between the two cultural dimensions and the two PPP measures. All of these H3 hypotheses a-to-d predict negative effects on firm size such that firm size will be smaller when the national culture variables, assertiveness or performance orientation are interacted with the PPP or Number of PPPs variables. In accordance with the core proposition of this research, all H3 hypotheses are supported. H3a, which relates a higher assertive orientation while having a PPP to firm size, is supported at the p < 0.01 level with a coefficient of −0.96. H3b, which relates a higher performance orientation while having a PPP to firm size, is supported at the p < 0.01 level with a coefficient of −2.29. H3c, which relates a higher assertive orientation while having more PPPs to firm size, is supported at the p < 0.05 level with a coefficient of −0.22. H3d, which relates a higher performance orientation while having more PPPs to firm size, is supported at the p < 0.05 level with a coefficient of −0.49. See

Table 6. Summary of Results.

Hypothesis		Result	Comments
H1a	Performance Orientation	-VE	Opposite result; performance orientation works better for smaller rather than larger inertial organizations.
H1b	Assertive Orientation	+VE	Supported; assertiveness may be necessary as a firm becomes larger and more inertial.
H2a	PPP	+VE	Supported; Having at least one PPP corresponds to larger firms.
H2b	Number of PPPs	+VE	Supported; the result is non-significant (NS) in Model 1 but significant in Models 3 and 5; An additional check suggests support that more PPPs relate to a larger firm *.
H3a	Assertive Orientation X PPP	-VE	Supported; higher significance and larger effect with PPP than Number of PPPs. This is negative as compared with H1b and H2a so the combination changes the outcome.
H3b	Performance Orientation X PPP	-VE	Supported; higher significance and larger effect with PPP than Number of PPPs.
H3c	Assertive Orientation X No. of PPPs	-VE	Supported.
H3d	Performance Orientation X No. of PPPs	-VE	Supported.

* Note: An additional check where Model 1 is run without the PPP variable shows the Number of PPPs variable as positive and significant so H2b is considered as supported.

for a summary of these results. Moreover, in consideration of the potential for collinearity of the PPP and Number of PPPs variable to effect the aforementioned results, all of the regressions were run again with only one of these variables, and the results are similar.

5. Discussion

PPP governance literature tends to take the perspective of the public sector rather than the private partner, and any partnership should work for all contributors [92]. Previous research has also identified the need to learn more about interrelationships in PPPs [93]. Thus, this study makes a much-needed contribution to the literature by examining PPPs from a firm perspective to consider the experiences of firms in PPPs. The study has empirically addressed the research questions, finding that: (1) a transportation firm can benefit from some aspects of a business-oriented national cultural context; (2) a firm likely benefits from engaging in PPPs; and (3) a firm’s background influences from a business-oriented culture can negatively affect its success in a PPP, as predicted. Overall, the core proposition that some cultural-contextual factors have different effects outside and inside partnerships is supported.

This research works out some of the PPP complications that recent research has remarked upon, validating claims that firms may face difficulties in PPPs [11]. It finds that the collaborative PPP orientation dominates over business-oriented national culture variables. Specific findings are that an assertive national culture is associated with larger firms and so is having one or more PPPs. However, combined conditions negatively affect the firm size. The assertiveness likely clashes with the collaborative public management requirement inside the PPP, so the results are that firms do not do as well and are smaller. Moreover, performance orientation inside a PPP has an even more negative effect than performance orientation on its own. The negative effect of performance orientation on its own is discussed next, but the outcome of the interaction is consistent with the previous statements in that the collaborative requirements of a PPP likely clash with a goal orientation reflected in the values of performance orientation.

Of note is that different business-oriented cultural characteristics can have different direct effects, as shown by the performance orientation variable that is not directly associated with larger firms, and instead has a significant negative effect. This is consistent with the entrepreneurship literature because smaller firms can be more flexible than larger firms in meeting performance expectations [94]. Thus, firms may not thrive and thereby become larger when under pressure from a national culture to perform; a more competitive market may keep firms smaller. Additionally, the possibility that the two national culture variables have different effects was foreshadowed by previous comments regarding [15]’s research. They defined a new combined (or latent) variable including performance orientation, but not including assertiveness and not explained by that research. This research triangulates the previous work because the two variables do have different effects. Moreover, assertiveness is a business-supporting value, so this research also extends previous research by clarifying the effects of an assertive culture.

Some previous PPP governance literature has paid attention to country differences in how PPPs are managed, which is not a focus of this research [11,95]. This research did not select on country for the firms or the PPPs and it happened that two-thirds of companies were US-based, with roughly half classified as sustainable firms. Out of twenty-eight countries represented, several firms were also from England, India, and Israel, and half of the three hundred firms were sustainable. Previous literature has suggested that there are different PPP governance styles across countries, but that these styles also vary with the particular PPP professionals involved; thus, mismatches in management perspectives within PPPs can be idiosyncratic [11]. This research controlled for country factors and suggests that no matter the management perspective within a PPP, it will still likely present problems for the more business-oriented firm, even sustainable firms. In this study, national culture is related to where the head office of the firm is located. This is the national culture that would most likely affect the behavior of the firm, no matter where the PPP is located [96,97]. Especially since most of the firms in the sample are small, they do not have extensive international operations outside their base location. Moreover, most international business literature would support the view that a firm, even a multinational corporation, is primarily influenced by its headquarters’ national (“home country”) culture [96,97]. So, if one were to argue that the national culture of the location where the transportation infrastructure is located—where the PPP is operating—was relevant, this research would not consider that a strong argument based on previous research and the results found here.

6. Conclusions

6.1. Contributions

Overall, this research makes several contributions. To institutional theory, it makes a contribution that the theory has power in the PPP context [13,14]. The results show resoundingly that it is the institutional orientation of the PPPs—the collaboration and requirement to cooperate with the government partner’s rules—as per institutional theory, which dominates over a national cultural orientation. Additionally, this study interacts national cultural dimensions (cultural-cognitive pressures) with an institutional context to show that culture potentially influences institutional outcomes. Particularly, private transportation firms entering into PPPs influenced by performance-oriented and assertive national cultural values experience negative effects on size in a PPP [34].

The study also contributes a firm perspective, unusual in the public administration literature, to confirm assumptions in the same literature that private partners experience challenges [11,95]. The challenges have consequential effects on firm success that may lead firms to choose private sector projects instead and/or may explain the contentious behavior by firms—to holdup projects, renegotiate terms, etc.—after they are working in the PPPs. Although this behavior may seem opportunistic and even corrupt which could be true [21], at the same time, firms may have justifiable issues sometimes that need to be seriously considered by other partners. Projects being delivered in the public interest, such as those addressing the aforementioned UN SDGs, will be furthered when all partners experience positive outcomes, and the private sector is incentivized to choose PPPs over private sector projects. Thus, this study informs transportation firms and policymakers so that they can arrive at earlier understandings and build trust for more productive outcomes [39].

6.2. Practical Implications

A practical implication of the findings for firms is that they should weigh other options in the private sector against engaging in PPPs. They should also be wary of some interfering national cultural factors. Firms may find ways to counteract these national cultural forces and work well in PPPs, recognizing that collaboration and public sector requirements of partnerships must be met or else opposing types of behavior will not be beneficial for any of the parties, including the firms [39]. Therefore, firms may reconsider non-collaborative tactics such as regular renegotiations and lawsuits often pursued after incorporating limiting conditions in PPP contracts to protect profits [95]. As previous theory suggests, firms with more experience (see the Firm Age variable in the models that is positive and significant but of small magnitude) do find success [11]. This experience could help them to learn how to be cooperative successfully, for example, by deciding to enter into PPPs where protective clauses are likely unnecessary and where they have room to move in case the public partner needs some extra consideration not anticipated originally in the contract.

Policymakers also learn from this research that PPPs do support increased employment in partner firms, often beneficial for communities [19]. However, external influences such as national culture must be considered to support more successful partnerships. Reducing hard pushes for performance may improve partnership outcomes, thus working in the public interest as well. At the same time, the public sector is broadly informed, perhaps useful across industry contexts and beyond the PPP context, by the performance outcome when evidence suggests that a competitive environment keeps firms smaller. On one hand, the public sector may want firms to grow and employ more people, but they may also be wary about firms becoming too dominant. Dominant firms may block smaller, more innovative new entrants, and there is also a threat of a loss of employment if the dominant firms fail because there are not sufficient other medium-sized firms to fill the employment gap [98].

6.3. Limitations and Future Research

A potential limitation of the research relates to the sample. Although it was not a research aim to study specific countries and country differences were controlled for, a more even representation of countries within the sample could have been helpful for developing specific country PPP policies. Previous research has been somewhat unclear about how relevant country differences are in PPPs because of the idiosyncratic nature of individual decisions and the tendency for PPPs to be managed in hybrid ways, not necessarily conforming to academic categories [11,95]. Thus, although this research provides some strong support for the firm perspective, no matter the country to support greater generalizability, future research could test this firm perspective using larger country-focused samples and/or by using country-focused case studies. Moreover, future research could subcategorize transportation firms based on mode and/or business models for more fine-grained investigations. Future research could also further investigate how age and experience, including the specific types of learnings of the involved firms affect PPP outcomes [11,92]. It would be useful to explore how to make PPPs more collaborative in case studies so that they do not so often devolve into antagonistic and costly bilateral contractual relationships. While this research is likely generalizable to other types of infrastructure PPPs in addition to the transportation PPPs of this research, future research could test the concepts of this work in other types of PPP contexts, as discussed by [66].