Thematic and Geographic Trends in Studying Smart Cities and PPP Projects: A Bibliometric Review ^†

Abstract

This study explores the relationship between public–private partnerships (PPPs) and smart cities in the literature that use information and communication technologies (ICTs) for sustainable urban development. This study explores, based on VOSviewer software 1.6.20, thematic and geographic patterns in academic articles (from Scopus) to identify central themes and knowledge gaps. The key findings highlight a lack of consideration of the African context in studying this subject and the prioritization of technological, governmental, and financial aspects more than social dimensions. The aim of this research is to guide policymakers, planners, and researchers by addressing these gaps to use as future recommendations.

1. Introduction

The urbanization of the 21st century has stimulated more demand for more ecologically sustainable, resource-efficient, and technologically advanced cities, facilitating global diffusion of smart city projects. Public–private partnerships (PPPs) have emerged as a vital financing and implementation vehicle for smart city projects, bridging public sector capacity gaps while tapping private sector finance and capability. Nonetheless, the connection between PPPs and smart cities is a new field, characterized by diverse regional approaches, unresolved governance challenges, and unequal research focus.

The thematic and geographic trends in the academic literature on smart cities and PPPs are examined using co-occurrence analysis of keywords and citation countries, through VOSviewer software, to identify dominant key themes and emerging areas. The results of this study make theoretical and empirical contributions by explaining gaps like the lack of attention to African context and by proposing directions for future research.

This study is addressed to policymakers, urban planners, and scholars to equip them with the information regarding the state of smart city-PPP research and the eventual gaps in the literature about smart cities and PPPs. In the end, this study creates a more nuanced understanding about the relation between PPPs and smart cities and how they can be used jointly.

2. Definition of Concepts

2.1. Smart City

A smart city is an urban city that utilizes information and communication technologies (ICTs) to enhance the quality of life for citizens, the efficiency of urban services, and sustainable development. The British Standards Institute (BSI) defines a smart city as “the effective integration of physical, digital, and human systems in the built environment to deliver a sustainable, prosperous, and inclusive future for its citizens” [1]. This definition emphasizes the importance of integrating various systems to create a cohesive and efficient urban environment.

Smart cities employ electronic data collection sensors located in infrastructures, buildings, vehicles, institutions, and devices (IoT, Internet of Things) to supply real-time information about the city’s operating systems, including energy, transportation, water supply, sewage, law enforcement, and information and communication [1]. These data are integrated into ICT platforms, allowing city managers and decision-makers to optimize the efficiency and resilience of city operations and services by connecting and commanding those systems remotely [1].

In addition to technological advancements, smart cities also foster participatory governance, increase collaboration among different economic actors, encourage innovative business models in both the private and public sectors, and promote sustainable urban development. The concept of a smart city has evolved over time, with various definitions highlighting different aspects such as community involvement, governance, and citizen-centered dimensions [2].

2.2. Public–Private Partnership

A PPP project is defined, by the world bank, as “A long-term contract between a private party and a government entity, for providing a public asset or service, in which the private party bears significant risk and management responsibility, and remuneration is linked to performance”. The objective of these projects is to enhance the development of countries by accelerating the construction of big projects necessitating a long time to be realized, big financial investments, and good technical expertise.

The principal advantages of PPP projects include delivering improved services and better value for money, primarily through appropriate risk transfer, encouraging innovation, greater asset utilization, and an integrated whole-of-life management, underpinned by private financing [3,4].

2.3. Examples of Smart Cities by PPP Projects

PPPs are one of multiple means of creating Smart cities; these are three examples [3]:

• Smart Nation initiative, Singapore: launched in 2014, which involves collaboration between the government, private sector, and citizens to transform Singapore into a sustainable, technologically advanced city. Key PPP projects include the development of a nationwide sensor network, the deployment of autonomous vehicles, and the creation of a Smart energy grid [5].
• Link NYC project, New York City, USA: New York City has utilized PPPs to address urban challenges through technology enabled solutions. This project is, for instance, a collaboration between the city government and a consortium of private companies to install a network of public Wi-Fi kiosks across the city. These kiosks not only provide free high-speed internet access but also serve as platforms for digital services, such as wayfinding, emergency alerts, and advertising [6].
• The Casablanca Smart City initiative, Morocco: launched in 2018, involves a collaboration between the Casablanca municipal government and a consortium of private companies. The project aims to modernize the city’s infrastructure and services through the implementation of digital technologies, such as a citywide sensor network, Smart traffic management, and integrated waste management systems. The public–private partnership has enabled the city to leverage private sector expertise and investment to accelerate the deployment of these Smart city solutions [7].

Following conceptual clarification, the subsequent section presents the analytical methodology for examining thematic and geographic trends while identifying critical knowledge gaps.

3. Materials and Methods

3.1. Research Subject

This study analyzed studies in the Scopus database, due to its comprehensive coverage of peer-reviewed journals and conferences, from 2015 to 2025. Scopus was additionally selected for its broader representation of non-Western scholarship, facilitating the identification of geographic imbalances in literature.

In general, this study aims to examine the scientific publication in this database relating “smart cities” and “PPP projects”. Documents were collected using the keywords “PPP” OR “public private partnership*” AND “smart cit*” (Table 1). The initial search yielded 205 papers. By limiting the research to only “English”, “articles”, the result becomes only ninety-one (91) articles, from 2015 to 2025. The search string utilized truncation (e.g., “smart cit*”) to capture relevant term variations such as “smart city”, “smart cities”, and “smart citizen”.

Table 1. Criteria for the analysis of trends in the literature on smart cities and PPP projects.

Items	Contents
Keywords	(“PPP” OR “public private partnership*”) AND (“smart cit*”)
Language	English
Document type	Article
Source	Scopus
Time interval	All (2015–2025)

Figure 1 illustrates the evolution of publications on this subject from 2015 to 2025. The ascending trend in document counts over this period reflects a growing academic and professional interest in the topic, suggesting its increasing relevance in the field.

Figure 1. The number of documents by year about PPP and smart cities.

3.2. Bibliometric Review

This study conducted a bibliometric review without limitation of publication year. The research question was set as ‘How do studies connect smart cities with PPP projects, and which regions are most prominently represented in this research?’ According to the research question, the analysis framework was set as follows.

First, a thematic analysis is conducted using VOSviewer by examining keyword co-occurrence to identify core themes. Second, the co-occurrence analysis is visualized to reveal distinct regional patterns in research and policy related to smart cities and PPPs.

By analyzing these elements, this study identifies what the trends are in studying smart cities and PPP projects. Furthermore, it highlights critical gaps in the literature, demonstrating both theoretical and empirical contributions.

4. Results and Discussion

4.1. Thematic Analysis via VOSviewer

By analyzing the titles and abstracts of the 91 articles in our study, a total of 702 words were detected. To keep only the relevant words, only those that have been repeated at least three times were retained, to have only 33 words. The most cited words are public–private partnership, smart city, sustainable development, sustainability, urban development, governance approach, and urbanization (see Figure 2).

Figure 2. Co-occurrence of keywords of articles linking smart cities and PPP projects.

There are also keywords like decision making, stakeholder, quality of life, innovation, smart infrastructure, artificial intelligence, and internet of things, which are also common.

Table 2 summarizes the key themes code keywords and describes the focus using references from the selected literature.

Table 2. Identified themes with code keywords and focus.

Themes	Code Keywords	Focus
Technology and Digitalization	Internet of Things (IoT), digital twin, surveillance	The deployment of sophisticated technologies such as IoT sensors, and urban modeling and surveillance systems using digital twins within smart city infrastructure [8,9,10,11,12,13,14].
Governance and Stakeholder Engagement	Governance, governance approach, stakeholder, government, civil society	Citizen, as part of civil society, as new stakeholder in the project (public–private–citizen) [15] and governance approach for PPP-driven smart cities [8,16,17,18,19,20,21,22].
Sustainability and Urban Development	Sustainability, sustainable development, urbanization, urban growth, urban planning	Harmonizing urban expansion at high velocity [23,24] with social and environmental sustainability targets [25].
Economic and Investment Strategies	PPP, investments, infrastructure	Financial models [26], private sector investment [27,28,29,30], and PPP contracts to support financing smart city developments [21,31].
Quality of Life and Innovation	Quality of life, innovation, smart city	Human-outcome-based solutions (e.g., livability, healthcare, mobility) [32,33,34,35,36] and innovative urban problem-solving solutions [27,37].
Conceptual and Methodological Frameworks	Conceptual framework	Theoretical models or methodologies of smart cities and PPPs analysis [26,38].
Geographic Focus	India	India is a specific context, suggesting case studies [16,39,40] or policy studies on Indian smart city proposals.

Table 2 elucidates the fact that the studies linking smart cities and PPPs give a big importance to clusters related to technology (e.g., Internet of Things (IoT), digital twin, surveillance), governance (e.g., approach, stakeholder, government, civil society), and finance (e.g., financial models, investments, PPP) more than clusters related to well-being of citizens (e.g., quality of life, healthcare, mobility).

The predominance of the ‘Technology and Digitalization’ cluster (Table 2) confirms the conceptual framework established in Section 2, wherein ICT integration constitutes a fundamental pillar of smart urban development [1]. Operationalized through high-frequency keywords such as ‘IoT’ and ‘digital twin’, this thematic concentration empirically validates the theoretical primacy accorded to technological systems in smart city paradigms.

4.2. Geographic Trends

The representation below is based on the number of citations, higher citation numbers correspond to a more central and prominent placement within the representation. Additionally, the spatial proximity between countries, indicated by the length of connecting arcs, reflects the strength of their academic collaboration, with shorter arcs denoting closer research ties.

This asymmetry means that current smart cities based on PPP models may undervalue the role of inclusive design and social impact in the long term, at the risk of technologically innovative yet socially fragmented solutions. If smart cities are to truly function for citizens, then citizen-oriented metrics need to be embedded within the core objectives of next-generation models, balancing innovation with real-life improvement. It is only on these terms that PPPs will be able to provide not just smarter infrastructure but also more habitable and equal urban spaces (see Figure 3).

Figure 3. Graph of country networks.

The overlay visualization (Figure 3) indicates a spatial change in cooperation leadership from Euro-Indian alliance (2018–2020) to Sino-Western networks (2022–2024), proof of the global scope of smart city studies. However, Italy and New Zealand’s recent inactivity suggests diverging regional agendas, and Africa’s absence underlines a critical imbalance in balanced knowledge production.

Table 3 lists researchers’ countries that have produced more than three articles about public–private partnerships (PPPs) and smart cities, as well as document numbers. The analysis of this table shows that China leads with 14 articles, suggesting wide-scale research or policy interest in PPPs and Smart Cities. India and the US are not far behind with 13 articles each, indicating strong academic, governmental, or private sector interest in these subjects. UK (8) and Italy (7) have moderate but substantial contributions. Hong Kong (5), Netherlands (5), Brazil (4), Canada (4), Germany (4), and UAE (4) have a minor but still substantial number of publications.

Table 3. Countries publishing more than three articles about smart cities and PPPs.

Country	# of Articles
China	14
India	13
United States	13
United Kingdom	8
Italy	7
Hong Kong	5
Netherlands	5
Brazil	4
Canada	4
Germany	4
United Arab Emirates	4

Talking about regional trends, this study elucidates that Asia (China, India, Hong Kong, UAE) dominates, suggesting rapid urbanization and PPP adoption; North America (US, Canada) and Europe (UK, Italy, Netherlands, Germany) show active research/policy discussions; Latin America (Brazil) is emerging in this field.

The dominance of the first three ranked countries (Table 3) suggests that smart city-PPP research is concentrated in countries with either strong state intervention (China, India) or robust private-sector ecosystems (US).

4.3. Research Gaps Identified

This study also emphasizes the main gaps in the selected literature (see Table 4).

Table 4. Main gaps in the selected literature about PPPs and Smart cities.

Identified Gap	Explanation
Need to learn from successful projects in the world to face challenges	For example, a study concluded that India should try to focus on holistic urban water resilience as China does with its Sponge City Program and that China should take a cue from India’s contractual and tender-based private service sourcing methods to tide over its financial setbacks in order to achieve its ambitious targets for 2030 [39].
Need to explore the dynamics of PPP implementation	Focus on longitudinal studies, comparative analyses, and case studies to further explore the dynamics of PPP implementation, assess long-term impacts and identify best practices for sustainable urban development [8,24,38].
Evaluate the role of PPPs in facing urban challenges	Research is needed to evaluate the role of PPPs in addressing emerging urban challenges such as climate change, digital transformation, and inclusive growth [8].
The lack of studies connecting Smart economies to Smart cities	There is a need for a comprehensive understanding of the interconnection between Smart economies and Smart cities. Although extensive studies exist on both smart economies and smart cities independently, there remains a notable gap in research that explores the specific processes and ramifications associated with the establishment of a smart economy in smart cities [10].
Update studies with recent data	A study requires further examination to determine whether their initial findings could inform future decision-making processes. It is about the article “Performance of an internet of things project in the public sector: The case of Nice smart city” that mentioned the need to collect more recent data about this project to confirm if the diffusion process follows the next S-curb theoretical steps of saturation and decline [12].
Investigating the equitable risk allocation for smart city PPPs	Due to the high level of technological innovation and information security requirements, it is essential to define the roles and responsibilities of both parties by investigating the equitable risk allocation scheme and risk/rewards sharing mechanisms and appropriate procurement model for smart city PPPs [18].
Replication of existing studies to other contexts	Future research should aim to replicate the findings across a broader range of cities and include cross-nation comparative analyses [19].
PPPs and conflict management	Issues related with public–private partnerships, potential conflict management, and co-creative process would be of interest in terms of governance [33].
The role of emerging technologies in shaping the future of Smart cities	Investigating how these new technologies (artificial intelligence, blockchain, and the Internet of Things, etc.) can be integrated into existing infrastructure and governance frameworks to enhance efficiency, transparency, and citizen engagement could provide valuable insights for policymakers and urban planners [38].
Smart cities with smart energy system	Radical policies towards zero greenhouse gas emissions (especially CO2), such as deep decarbonization, will also change the business model in smart cities. Many industrial sectors have already developed strategies to move towards net zero [38].

This table is a valuable reference for all the stakeholders in public–private partnerships (PPPs) and smart city projects by bringing to their notice relevant research gaps:

• For scholars, it identifies priority areas to be researched in more detail, such as longitudinal PPP analysis, inter-linkages between smart economy and smart city, and the impact of innovative technologies, and provides the first step for more in-depth academic study.
• Policy makers and governments can leverage these gaps to establish evidence-based strategies such as implementing cross-country best practices (e.g., the Sponge City Program of China or tender-based approaches of India) to alleviate urban resilience and finance concerns.
• The emphasis on equitable risk distribution and dispute settlement allows private sector partners to be assured about collective governance, and the need for up-to-date data and contextual replication ensures urban planners and practitioners make choices based on the most relevant current evidence.
• Finally, the decarbonization and inclusive growth imperative speaks to global sustainability agendas, involving multidisciplinary collaboration to manage climate change and digitalization.

Through completing these gaps together, all stakeholders can facilitate more equitable, sustainable, and technologically enhanced smart cities through effective PPP models.

5. Conclusions

This study has analyzed thematic and geographic trends in research on public–private partnerships (PPPs) and smart cities. The aim was to address the research problem of challenges related to fragmented knowledge and the demand for more academic attention to regions. By examining document counts, keyword co-occurrence, and regional contributions, this study has answered the research question about the dominant themes and geographic patterns in smart city-PPP research, and where do gaps exist?

In the thematic analysis, this study has demonstrated that there are multiple research clusters around technology (IoT, digital twins), governance (stakeholders, sustainability), and finance (PPPs, investments).

In the geographic trends, Asia (China, India) dominates in volume, reflecting state-driven urbanization agendas. North America (US) and Europe (UK, Italy) emphasize governance and climate resilience. However, the underrepresentation of Africa, Latin America (except Brazil), and Southeast Asia highlights a Global South research gap.

The findings reveal that smart city-PPP research focuses more on technological, governance, and financial aspects, often at the expense of social outcomes. This aligns with visible critiques of smart urbanism as an elite-driven, technocratic project that prioritizes efficiency and innovation while marginalizing the needs of populations.

As future research recommendations, this study outline the need to decenter knowledge production by expand studies on African, Latin American, and Southeast Asian smart city-PPP experiments. This study recommends also to integrate critical urban theory, data ethics, and participatory design into PPP frameworks. Policymakers should prioritize targeted funding for underrepresented regions and institutionalize social metrics in smart city frameworks to address the identified gaps in equitable urban development.

Additionally, the research gaps identified in this study serve as futures directions to help all stakeholders involved, including those engaged in PPPs and smart cities, to explore more specific areas of research on the topic. Table 4 discusses key gaps in PPPs and smart cities and guides researchers to studies needed, policymakers to pilot-tested models, and private partners towards balanced risk frameworks. Integrating cross-border best practice, the integration of technology and the strategy for sustainability enables the stakeholders to co-create resilient, inclusive urban solutions.

This study present different limitations like language bias, because of the choose of one language (English) which may exclude key non-Western perspectives, and the use of one database (Scopus), omitting the gray literature (e.g., government reports). The bibliometric review relies on document counts that reflect activity but not necessarily policy effectiveness.

This study underscores the need for more inclusive, critical, and practice-informed research on smart city PPPs. By addressing geographic and thematic imbalances, future work can better inform equitable urban governance and context-sensitive policy design.