1. Introduction

1.1. Background

The global shift toward sustainable urban mobility is emerging as a critical solution to counter the growing environmental and social challenges that cities face today. With urban populations expanding, traditional transportation systems are increasingly strained, leading to traffic congestion, pollution, and diminished quality of life. Public transportation is at the heart of strategies to reduce these impacts, particularly by promoting low-carbon options such as electric vehicles (EVs), metro systems, and light rail [3].

Green public transportation projects—ranging from electric buses to multimodal transport systems—are central to this transition. They not only reduce greenhouse gas emissions but also offer more efficient and accessible alternatives to conventional transport modes. However, these projects require effective integration of sustainable project management (SPM) practices with the technical and operational demands of the transportation sector (Silvius & Schipper, 2014). The intersection of environmental sustainability, technological innovation, and economic feasibility represents a significant challenge for urban planners and policymakers alike.

1.2. Research Significance

This paper investigates the challenges of implementing sustainable project management in green public transportation initiatives. These projects are often large-scale and complex, involving a broad spectrum of stakeholders including government agencies, private investors, transport operators, and the general public. Despite their potential benefits, green transportation projects face significant hurdles in areas such as financial planning, technological integration, regulatory alignment, and stakeholder management.

1.3. Research Questions

• How can financial constraints, such as high upfront costs and the difficulty of securing investment, be addressed?

• What are the technological challenges associated with integrating green technologies into existing urban infrastructures?

• How do regulatory frameworks and policy delays affect the implementation and scaling of green transportation systems?

• What are the best practices for stakeholder engagement and conflict resolution in multi-stakeholder environments?

Through a comprehensive review of the literature, this paper aims to provide a nuanced understanding of these challenges and how established project management methodologies—such as PRINCE2, Lean, and Agile—can address them.

1.4. Research Objectives

• To explore the principal challenges that sustainable public transportation projects face in the context of project management.

• To critically assess the effectiveness of established project management methodologies (PRINCE2, Lean, and Agile) in addressing these challenges.

• To examine real-world case studies of green public transportation projects and derive lessons on best practices.

• To provide actionable recommendations for improving the planning, financing, and implementation of green transportation projects.

2. Literature Review

2.1. Sustainable Project Management in Public Transportation

Sustainable project management (SPM) is a holistic approach that integrates environmental, social, and economic sustainability across the project lifecycle. In public transportation, it involves not only reducing the carbon footprint of transport systems but also ensuring that these systems contribute to long-term economic viability and social equity (Silvius & Schipper, 2014). As cities embrace green technologies such as electric buses or solar-powered transit stations, the challenge remains to balance these technological advancements with public accessibility and affordability, especially for vulnerable populations (Zheng et al., 2021).

SPM's adoption in public transportation is critical to achieving global sustainability targets such as net-zero carbon emissions by 2050. However, large-scale projects often face hurdles related to stakeholder alignment, financing, and regulatory delays, making the practical application of SPM an ongoing challenge (Hickman et al., 2017).

2.2. Key Challenges in Sustainable Project Management

2.2.1. Financial Constraints

One of the most pressing issues in sustainable transportation is securing adequate funding for capital-intensive green technologies. Electric buses, renewable energy infrastructure, and multimodal transit solutions all require substantial upfront investment, which can be a significant barrier, particularly in developing cities or regions with tight budgets (Dimitriou & Gakenheimer, 2011). Financial constraints are compounded by the difficulty of attracting private investment, given the perceived risks associated with long-term payback periods and the unproven profitability of green transport solutions (Butler et al., 2020).

To mitigate these challenges, innovative financing mechanisms such as green bonds, carbon credits, and public-private partnerships (PPPs) are increasingly being explored (Stern & Macey, 2019). These models allow for risk-sharing and enable the diversification of funding sources, which is particularly crucial in low- and middle-income countries (Zawieska & Pieriegud, 2018).

2.2.2. Technological Challenges

Technological integration is another major obstacle. Existing transport infrastructure in many cities is ill-equipped to accommodate green technologies such as electric buses or energy-efficient rail systems. Retrofitting ageing infrastructure, particularly in older urban areas, involves significant costs, logistical challenges, and long timelines (Mok et al., 2015). Moreover, ensuring that newly implemented technologies are interoperable with legacy systems can complicate integration, particularly when technologies are rapidly evolving (Tariq, 2024).

The need for a scalable and standardized charging infrastructure is particularly critical for electric vehicles (EVs). A lack of uniform charging networks is a significant barrier to the widespread adoption of electric buses and cars in public fleets. To overcome this, cities must prioritize investments in standardizing charging stations and exploring digital solutions like smart grids that can facilitate real-time data exchange between vehicles and charging stations (Hickman et al., 2017).

2.2.3. Regulatory and Policy Barriers

Regulatory frameworks for green public transportation are often fragmented and slow to evolve, which can delay the implementation of projects. The absence of standardized regulations for emissions, vehicle certification, and environmental impact assessments across jurisdictions adds to the complexity (Silvius & Schipper, 2014). Furthermore, as technologies evolve, so too must regulatory standards, but policy reforms often fail to keep pace, resulting in significant delays and inefficiencies.

International collaborations on regulatory harmonization and the development of local "innovation centres" for green transport solutions have proven to be effective strategies. For example, the EU has spearheaded efforts to streamline emissions standards across member states, which has contributed to the success of several large-scale urban mobility projects (Torrisi et al., 2020).

2.2.4. Stakeholder Conflicts

One of the inherent complexities of green public transportation projects is the involvement of multiple stakeholders, each with differing priorities and interests. Government agencies may prioritize public welfare and environmental goals, while private investors are often more concerned with return on investment (ROI) and profitability. Local communities may resist changes to infrastructure due to concerns over disruption and job security, particularly when public transport operators face automation through smart mobility solutions (Zheng et al., 2021).

Effective stakeholder management, including clear communication and negotiation strategies, is critical to overcoming these challenges. Engaging stakeholders early in the planning process, conducting regular consultations, and creating avenues for collaboration can help align conflicting interests and ensure project success (Mavlutova et al., 2023).

3. Methodology

This study employs a case study approach to explore the challenges and strategies in sustainable project management for green public transportation projects. By focusing on two distinct case studies, the Asian Development Bank (ADB) Green Transport Initiative and the European Investment Bank (EIB) Sustainable Mobility Project, this research seeks to provide a comprehensive analysis of the common obstacles and strategies that shape the successful implementation of such projects. Both cases were chosen for their significant impact on green transportation in their respective regions, with a focus on financing, technology integration, stakeholder management, and policy barriers.

The research integrates both qualitative and quantitative methods. Qualitative data is collected through semi-structured interviews with key stakeholders involved in each project, including project managers, government officials, technical experts, and investors. These interviews focus on understanding the practical challenges and decision-making processes in the projects, such as the financing mechanisms, regulatory hurdles, and the management of conflicting interests.

In addition to qualitative data, quantitative data is gathered from secondary sources, such as project reports, financial records, and environmental impact assessments. This allows for an empirical evaluation of the projects, providing key performance metrics like carbon emission reductions, return on investment (ROI), budget deviations, and project timelines. The combination of qualitative and quantitative data will be analyzed using content analysis, thematic analysis, and statistical methods, providing a holistic view of the management strategies and their outcomes in green public transportation projects.

4. Case Studies and Comparative Analysis

4.1. Asian Development Bank (ADB) Green Transport Initiative

The ADB Green Transport Initiative focuses on advancing sustainable urban transport systems in the Asia-Pacific region by promoting the adoption of electric buses, taxis, and intelligent transportation systems. A major challenge for this initiative has been financing. While ADB provides significant initial funding, the high upfront costs of electric vehicles and supporting infrastructure have created barriers for several participating countries. In response, the initiative has utilized green bonds, public-private partnerships (PPPs), and government subsidies to secure additional funding. Despite these efforts, the financing structure remains an ongoing challenge, particularly in nations with limited access to capital markets or poorly developed financing mechanisms.

Technologically, integration issues have also been a key challenge, particularly due to the varying levels of infrastructure development across the countries involved. Some regions face limitations in electricity grid capacity, while others lack sufficient charging stations, resulting in a mismatch between the adoption of electric vehicles and the availability of supporting infrastructure. ADB has worked closely with local governments and technical experts to develop context-specific technological solutions, yet challenges persist, particularly regarding the interoperability and scalability of electric transport systems.

Finally, stakeholder management has proven difficult, as various groups have different priorities. Local communities often resist changes in transportation routes, while environmental advocates demand more rapid decarbonization. ADB has addressed this by engaging in extensive public consultations and multi-stakeholder meetings, aiming to align the needs of diverse stakeholders and minimize conflicts.

4.2. European Investment Bank (EIB) Sustainable Mobility Project

The EIB Sustainable Mobility Project is a similar initiative aimed at reducing carbon emissions and promoting green transportation across European cities. The project prioritizes the electrification of public transport fleets, including buses and taxis, alongside the development of car-sharing programs and energy-efficient transportation hubs. One of the primary challenges faced by the EIB project is financing. Like the ADB initiative, the EIB project requires significant initial capital for infrastructure development, and it has employed a mix of loans, public funding, and PPP models to meet these demands. However, despite these efforts, the high initial cost remains a major hurdle, and the pace of implementation has been slower than initially expected in some cities.

From a technological perspective, the EIB project benefits from relatively advanced infrastructure in Europe. However, challenges still arise with charging networks and grid integration. As electric vehicle adoption outpaces the growth of charging infrastructure in some cities, the integration of electric vehicles into the existing transport network becomes increasingly complex. The EIB has worked with local authorities to address these issues by improving grid capacity and expanding the charging network, yet logistical difficulties remain.

A significant challenge for the EIB project lies in overcoming regulatory and policy barriers. Although the EU has ambitious climate goals, the alignment of national policies and local regulations with these objectives has been slow in certain areas, causing delays in the implementation of some aspects of the project. This highlights the importance of aligning technological and financial solutions with effective regulatory frameworks to ensure the timely success of sustainable transportation initiatives.

4.3. Comparative Analysis

A comparative analysis of the two projects reveals both similarities and differences in their approaches to managing green public transportation projects. Both initiatives share the common goal of reducing carbon emissions and promoting sustainable urban mobility. However, the financing mechanisms employed differ significantly, with ADB leveraging green bonds and public-private partnerships more heavily, while EIB relies on loans and public funding.

In terms of technology integration, the EIB project benefits from a more developed infrastructure in Europe, enabling smoother integration of electric vehicles and supporting systems. However, the charging network remains a challenge in both projects, underscoring the importance of a robust and scalable infrastructure to support the widespread adoption of electric transport.

Stakeholder engagement remains a key challenge in both initiatives, with differing groups of stakeholders often presenting conflicting interests. However, both projects have sought to address these issues through effective communication strategies, including public consultations and multi-stakeholder engagements. This highlights the necessity of involving a broad range of stakeholders early in the project planning phase to ensure alignment and support for the project’s objectives.

Lastly, both case studies underline the importance of context-specific strategies when dealing with regional disparities in infrastructure development, financing capacities, and technological requirements. ADB and EIB have demonstrated flexibility and adaptability in their approaches, emphasizing the need for tailored solutions to address the unique challenges faced by each region.

5. Discussion and Recommendations

The implementation of green public transportation projects involves addressing a wide range of challenges, particularly in areas such as financing, technological integration, stakeholder management, and regulatory frameworks.

5.1. Financing and Financial Sustainability

Securing sufficient financial resources remains one of the most significant challenges for green public transportation projects. The high upfront capital required for infrastructure, such as electric and hybrid transport systems, renewable energy integration, and advanced digital management technologies, can deter both public and private investors. For instance, the initial costs of electric buses, the expansion of charging networks, and the modernization of electricity grids often represent substantial financial barriers, particularly in low- and middle-income countries or regions with limited access to capital markets (Banister, 2019; Dimitriou & Gakenheimer, 2011).

To address these challenges, innovative financing mechanisms have become essential. Blended financing models that combine public funds, private investments, and international development assistance can help distribute risks and ensure long-term financial sustainability (Silvius & Schipper, 2014). Green bonds have proven to be an effective tool for raising capital for low-carbon transport projects, with institutions such as the Asian Development Bank (ADB) and European Investment Bank (EIB) successfully utilizing them to finance sustainable urban mobility projects (Mok et al., 2015). Carbon credits, which reward projects for reducing greenhouse gas emissions, also provide financial incentives that can increase investment appeal (Dimitriou & Gakenheimer, 2011).

Additionally, public-private partnerships (PPPs) play a crucial role in mobilizing private-sector capital while sharing financial risks with the public sector. Performance-based financing models, such as "pay-as-you-save" schemes, can further encourage private sector investment by linking financial returns to measurable environmental and operational improvements (Stern & Macey, 2019). Long-term financial sustainability also hinges on the exploration of new approaches, such as impact investing, which focuses on both financial returns and positive environmental outcomes (Smith & Lee, 2021).

5.2. Technological Integration and Infrastructure Challenges

The successful transition to green public transport relies heavily on the integration of advanced technologies. However, this requires substantial investments in infrastructure modernization and digitalization, which are often challenging to implement in existing transport systems (Zheng et al., 2021). One of the key challenges is the lack of standardized charging infrastructure for electric vehicles (EVs), which can hinder widespread adoption. To address this, cities must prioritize the development of unified charging networks and establish internationally recognized interoperability standards to ensure compatibility across regions (Mok et al., 2015). Furthermore, integrating smart transport management systems—such as AI-powered traffic optimization, IoT-enabled fleet monitoring, and predictive maintenance—can significantly enhance system efficiency, reduce operational costs, and improve the overall user experience (Hickman et al., 2017).

Governments should also foster open data policies, allowing both public and private stakeholders to collaborate on improving transport systems. Initiatives like the EU’s Open Transport Data Directive have proven successful in providing real-time passenger information systems that reduce reliance on private vehicles and improve urban mobility (Stern & Macey, 2019). Additionally, substantial investments in research and development for energy storage technologies, including solid-state batteries and hydrogen fuel cells, are essential to the viability of large-scale electrification in public transport systems (Dimitriou & Gakenheimer, 2011).

5.3. Regulatory and Policy Barriers

A stable and clear regulatory framework is crucial for the success of green transportation projects. One of the most significant regulatory challenges is the inconsistency of emissions standards across regions, which creates uncertainty for investors and project developers (Silvius & Schipper, 2014). Harmonizing emissions regulations internationally could foster cross-border collaboration and help accelerate the global transition to sustainable transport (Stern & Macey, 2019). In the ADB and EIB projects, slow regulatory approvals and inconsistent local policies have delayed the implementation of key components, such as electrifying bus fleets and building charging stations [3].

To mitigate these challenges, governments must streamline project approval and permitting processes. Establishing fast-track approval mechanisms for projects that meet predefined sustainability criteria can help expedite the deployment of green transport solutions (Hickman et al., 2017). Additionally, integrating sustainability criteria into public procurement policies can create market signals that encourage the private sector to invest in and support green transport systems. Countries such as Norway and Germany have successfully implemented fiscal policies, including tax incentives for electric vehicles, to promote the adoption of sustainable transport technologies [3].

5.4. Stakeholder Engagement and Public Awareness

Effective stakeholder engagement is critical to the success of green public transportation projects. Balancing the interests of various stakeholders—such as local communities, government agencies, environmental groups, and private sector actors—often poses challenges. In both the ADB and EIB initiatives, stakeholder management has played a crucial role in shaping the direction and success of the projects. For example, local communities in certain regions have expressed concerns over the displacement of traditional bus routes by electric buses or the costs associated with subsidies for green transport systems. Conversely, environmental groups have advocated for faster adoption of electric vehicles and stronger regulatory measures to reduce emissions.

Addressing these competing interests requires transparent and inclusive decision-making processes. Public consultations, multi-stakeholder meetings, and ongoing communication are vital for ensuring that the voices of all stakeholders are heard and that conflicts are minimized (Zheng et al., 2021). Public awareness campaigns also play a significant role in encouraging behavioural shifts towards sustainable transport. Educating the public on the benefits of green transit systems—such as reduced emissions, improved air quality, and cost savings—can help reduce reliance on private car ownership and boost the adoption of eco-friendly public transportation options (Dimitriou & Gakenheimer, 2011).

6. Conclusion

The study of sustainable project management in green public transportation projects highlights the complexities and challenges inherent in implementing such large-scale initiatives. By examining the experiences of the ADB and EIB projects, it is clear that while there is no one-size-fits-all approach, certain key strategies can facilitate success.

Innovative financing mechanisms, such as green bonds and public-private partnerships, are crucial for overcoming the substantial upfront costs of green transport infrastructure. However, ensuring long-term financial sustainability demands exploring performance-based financing models and impact investment. Addressing technological and infrastructure challenges also requires close collaboration between public authorities, the private sector, and utility companies to scale the adoption of electric vehicles. This involves not only investment in charging networks but also the development of standardized, interoperable technologies to support a global transition to green transport. Equally important is stakeholder engagement, as balancing the interests of local communities, environmental groups, and the private sector can be difficult. Transparent and inclusive decision-making processes can help mitigate conflicts and build broad support for sustainable transportation projects. Finally, policy alignment across all levels of government is essential for creating a conducive environment for green transport initiatives. Governments must work to eliminate regulatory barriers, streamline approval processes, and create policies that incentivize private sector investment and support for green transport systems.

As cities and regions continue to grapple with the challenges of climate change and urbanization, green public transportation initiatives will play an essential role in achieving sustainable mobility. Through careful management and strategic decision-making, these projects can lead the way toward a more sustainable and equitable future.