The construction industry plays a vital role in national economic development. The public sector's construction industry directly affects the global economy; it is a strategic field that makes a tangible contribution to the economic growth of developing countries. Nationwide, the construction sector is considered one of the most dynamic and promising sectors of the national economy, as it provides the necessary infrastructure, strengthens other sectors, and reduces unemployment [1]. However, the performance of this important industry is highly influenced by various factors that, if not considered in the earlier stages of every project, can result in unsuccessful implementation. Achieving project goals and objectives depends on various factors, one of which is effective risk management practices.

The occurrence of risks in large projects implemented in Tanzania has become a topic of debate in this era. This is because implementing megaprojects faces many challenges regarding resources, funding, environment, and management [2]. Despite experiencing these persistent problems, the Tanzanian construction industry has not implemented risk assessment and management practices (RAMP) at a satisfactory level that can indicate the willingness of the industry to overcome these challenges. A study [3] claims that the major problems behind unsuccessful RAMP implementation in Tanzania include awareness of risk management processes, lack of experience, and lack of information.

Expected benefits from infrastructure developed in Tanzania and many other developing countries have been obstructed by mismanagement of construction projects, resulting in a lack of value for money. Rwezaura [4] points out that to obtain value for money invested in construction projects, much consideration must be put into ensuring that experienced experts consider and perform all risk management phases. The reason why effective management of all phases of a project is highly encouraged is that the performance of every stage has an impact on the general performance of a project. Conversely, experience shows that project implementing agencies put much effort into the execution phase, which results in a high chance of many risks as there was no effective risk assessment at the initial stages. According to Schieg [5], successful risk management involves all areas, processes, and parties of the project; each individual must be committed and have risk awareness. Buzzetto et al., [6] advocate that procurement is the most challenging stage of the project lifecycle, which requires great attention to ensure that the project succeeds from the preliminary stage to the end. It is also highlighted in the study [7] that the most significant risk factors in railway projects originated from design works; therefore, an emphasis should be put on using experienced professionals in design works and conducting an effective geotechnical investigation.

Unfortunately, despite the Tanzanian government's efforts in project risk management ineffective risk management has been a persisting challenge in many projects that are implemented, which is why some projects experience schedule delays [8]. Furthermore, projects fail to complete at a reasonable cost owing to changes or insufficient budgets, disputes that arise, and ambiguities among the parties, which are common occurrences in African projects, including those in Tanzania [9]. It should be noted that any risks, such as disputes, payment delays, and poor contractual management, are attractive for project delays. Moreover, the top causes of delays in construction projects are price fluctuations or inflation, government bureaucracy, and inadequate payments by the fundraiser or government [10].

In recent years, investigations and audit reports from the Controller and Auditor General (CAG) and Public Procurement and Regulatory Authority (PPRA) have shown that several projects conducted by Tanzanian government agencies, such as water supply and road construction, have not been performed satisfactorily [11]. Project achievements are limited by inadequate funding, planning, and pricing of the project; incapability of the contractor; fire; failure to select contractors and suppliers; inappropriate contract awards; insufficient delivery methods; and poor survey of the site [12]. In their study [13], Kullaya et al. state that in the past ten years, overspending has been one of the challenging problems in Tanzanian road construction projects.

The aforementioned studies addressed the importance of risk management in the construction industry and the impact of implementing RAMP. However, in the context of the Tanzanian construction industry, most studies have focused only on building and road projects. Owing to the increased government investment in other transport projects, particularly railways, there is a need to determine the risk factors associated with these projects and provide appropriate recommendations. Therefore, this study analyzes the key risks in railway projects in Tanzania. Therefore, this study was conducted to analyze risks associated with railway construction projects in Tanzania by answering the following three questions: (i) What are the risk factors associated with railway construction projects in Tanzania? (ii) How can the key risk factors of railway projects in Tanzania be determined and ranked based on their possibility of occurrence and degree of impact? (ii) How do various stakeholders perceive and prioritize the identified risks in railway construction projects in Tanzania?

Various Scholars have conducted studies on construction project risks and classified risks into different ways. For example, Gashaw and Jilcha [14] grouped risks into design, construction, management, resource, contractual and legal, and external risks. Boateng et al. [15] classified risks into social, technical, economic, environmental, and political risks. According to Damoah and Kumi [16], construction project risks can be categorized into leadership, management and administration practices, resources, and external forces. A study [17] conducted in Italy divided risks into internal and external risks. Kassem et al. [18] identified 13 main risk categories in construction projects in the oil and gas sector in Yemen. These categories are 1. Client-related 2. Contractor-related 3. Consultant-related 4. Feasibility study and design-related 5.Tendering and contract-related 6. Resource and material supply-related 7. Project management-related 8. Country economic-related 9. Political risk-related 10. Local people-related 11. Safety and environment-related 12. Security risk-related 13. Force majeure-related. Another study [19] identified seven groups of risks in freeway PPP projects: financial, legal, technical, environmental, social, force majeure, and organization and coordination.

The failure of construction projects can occur for various reasons, encompassing both internal and external factors. These failures can lead to cost overruns, schedule delays, compromised quality, and even complete project abandonment. To understand the key factors for construction project failure, a comprehensive review of the relevant literature was conducted. Shahhossein et al. [20] propose a methodology for identifying the root causes of construction project failure using Fault Tree Analysis (FTA) and Linguistic Weighted Average (LWA) with the help of fuzzy theory. The study identifies financial concerns and shortcomings of the bidding process as the major causes of project failure. The study [14] was conducted on risk prioritization using a fuzzy analytic network process for the Addis-Djibouti railway construction project. Its results show that the right-of-way is the top risk with the highest impact on time and cost, followed by construction errors and incomplete contract details.

It is argued in [16] that political interference, delays in payment, partisan politics, bureaucracy, corruption, poor supervision, lack of commitment by project leaders, poor planning, starting more projects than the government can fund, and change in government are the top ten factors that contribute to government construction projects failure in Ghana. Another study conducted in Ghana [21] found that, of the 25 risk factors studied, five factors with a high probability of occurrence in construction projects include price fluctuations, delays in payment, inflation, quality and performance control, and poor financial markets. The critical factors containing failure and abandonment of public sector construction projects in Nigeria include effective monitoring, understanding of project mission, technical know-how of the project manager, support from top management, political risks, effective procurement process, provision of adequate finance by the client, and effective communication and information management by the design team [22].

Process quality during construction projects in Pakistan is influenced by the selection of an appropriate contractor, supervision by owner representatives, management leadership, teamwork, and quality of drawings and specifications received from designers [23]. It is also argued by Nawaz et al. [24] that the factors preventing project success include scope changes, project budget overruns, schedule delays, unfulfilled quality standards, technical specifications not followed, and complaints and claims. Kassem et al. [18] adopted a case study methodology to investigate the risk factors in construction projects in oil and gas processing facilities in Yemen. The authors collected data through interviews, document analysis, and site visits. Their study found that internal risks are the greatest influential factors in construction projects in the oil and gas sector, followed by changes during construction projects, government instability, incorrect project cost estimation, government delay in decision-making, incorrect project schedule estimation, and political situation and war in the country. A study [25] employed a comprehensive review of the literature and expert opinions to identify and analyze critical risk factors specific to international construction projects in India. Its findings highlight several major risk factors, including inadequate project planning, poor project feasibility assessment, insufficient experience in international projects, cultural differences, political and regulatory uncertainties, and lack of effective communication and coordination among stakeholders.

According to a study [26], project costs, time, and quality are the key indicators determining the success of a project, which means that when delays occur during the implementation phase, the achievement of project goals and objectives is limited. The risk of delay affects clients, consultants, contractors, mistrust, cash flow, and litigation. Project risks increase delays as they tend to change the implementation schedule, a factor that limits project milestones. A competent project management team ensures that all risks are identified, assessed, evaluated, shared, or measured to avoid their impact on quality, cost, and time [27]. For developing countries like Tanzania, managing all project risks is complex. A study [28] explains that developing countries are challenged with risks in the implemented construction megaprojects owing to limited funds for implementation, poor technologies, adequacy of equipment, limited experience, increasing unnecessary costs, and changing weather conditions. This study [29] revealed that the inflation rate is neglected by most developing countries when implementing various construction projects; however, it is highly beneficial. Project budgeting and all economic matters diverge from including inflation rate impacts, a factor leading to project cost overruns, particularly in labor payments, machinery hire, and material building prices. It is recommended that budgeting employs inflation rate principles to eradicate project cost overrun challenges. Recent studies conducted in Tanzania [13, 30, 31] have identified schedule delays, variation orders, and cost overruns as serious problems affecting road project performance. The studies highlighted financial problems, selection of incompetent contractors, poor site management during project execution, weather conditions, differing site conditions, changes in design, poor scheduling, unavailability of equipment, lack of communication, and unrealistic work programs as significant factors.

After reviewing the literature, 24 risk variables categorized into 7 groups (Table 1) were found to be relevant to the Tanzanian construction industry and were therefore selected for use in this study.

Transport infrastructure, the railway in particular, has a significant impact on the development of Tanznaia's economy due to the geographical nature of the country as it is surrounded by many landlocked countries which use the main ports of Tanzania for import-export activities. Railway projects are among the mega projects implemented by the Tanzanian government as a strategy for improving the transport infrastructure network. Therefore, determining the risk factors associated with these projects is important as it helps projects implementing entities to prepare a risk management plan in accordance with the likelihood of occurrence of specific risks and their level of impact on project performance. The existing literature shows that numerous studies have been conducted to determine factors causing construction project failure. However, a few studies have focused on the construction risk factors of railway projects. Further, the literature review conducted in this research found no study focused on the risks of railway projects in Tanzania. Researchers in this study collected data through a questionnaire survey of 77 respondents, and as a result of statistical analysis, they ranked risks associated with railway projects in Tanzania. The results indicate that the prevailing risk categories are government and political, financial, economic, and technical risks.

Regarding the probability of occurrence, the results showed that the top ten risk factors are: delayed payments; cost overrun; political pressure; design changes; inadequate project planning; price fluctuation; bureaucracy; changes in the scope of work; quality and performance control; and delay in land acquisition. In addition, our results show that the three groups have different views on ranking five risk factors, namely: political pressure, design changes, changes in the scope of work, lack of commitment, and inappropriate contract award.

The results of risk impacts on project performance indicate that the top ten critical risk factors are delayed payment; cost overrun; political pressure; financial bankruptcy; delay in land acquisition; poor performance of contractors and consultants; inadequate project planning; quality and performance control; inappropriate contract awards; and price fluctuation. The results also indicate that there is no significant difference between the points of view of the groups (i.e. contractors, consultants, and clients), with the exception of one risk factor. The Kruskal-Wallis test found a significant differences between the groups for the “political pressure” which is a risk factor under the government and political risks category.

The findings presented in this study can provide significant insights regarding adequate pre-project planning, effective risk management, and other measures that can be taken to reduce the risk impact. Although this study focused on risk factors associated with railway projects in Tanzania, its findings may be useful to other infrastructure projects to be implemented in developing countries. These results will also be useful for local and foreign companies which plan to invest in infrastructure projects in developing countries.

For successful implementation of railway projects, the following recommendations are proposed:

(i) Considering that financial and economic risk factors of delayed payment and cost overruns are the key factors, it is important to improve project management practices. Risk assessment must be carefully conducted from the preliminary stages. It is highlighted in [38] that RAM (Reliability, Availability, and Maintainability) demonstration is essential during the planning, design, and implementation stages of railway projects to assess the system's reliability, availability, and maintainability characteristics.

(ii) Government should improve coordination and communication between government agencies involved in construction projects. Regular interdepartmental meetings, shared databases, and collaborative decision-making can help minimize bureaucratic delays and ensure a smoother process. Rewards can also be an effective tool when used as part of a broader anti-corruption strategy. Mario and Igor [39] argue that a balance between intrinsic and extrinsic rewards is necessary to improve job satisfaction and reduce corruption in the public sector.

(iii) Political interference is very common in most developing countries. Politician influence may affect project estimates and scope, resulting in cost overruns and delays. Government should establish robust mechanisms and processes that prioritize transparency, accountability, and professional expertise. Transparent procurement processes, independent regulatory bodies, and strengthened legal frameworks are among the important areas that the government should observe.

(iv) Strengthening institutional capacity to ensure decisions making in different aspects of railway projects are based on professional expertise. This can be achieved by investing in building the capacity of government institutions responsible for managing construction projects through training on project management, procurement procedures, and ethics. Workshops also can be an effective way of building capacity within organizations and government institutions; they provide opportunities for training, learning, and skill development in a focused and interactive environment. Authors in the study [40] propose using a risk management workshop as an approach to identify, evaluate, and manage risks in railway construction projects in Iran.

(v) Government partnering with private companies in railway construction projects through different PPP models might help to reduce some risks. According to Lee et al. [41], BTO-rs (Build-Transfer-Operate with Risk Sharing) can decrease public and private sectors costs and reduce risks; however, implementing a railway project with BTO-rs requires more meticulous preliminary examinations.