THE EFFECT OF DOMESTIC PUBLIC INVESTMENT ON NIGERIA'S ECONOMY: A STUDY OF THE TRANSPORTATION SECTOR

CHAPTER ONE

INTRODUCTION

1.1 Background of the Study

Public investment serves as a foundational driver of economic growth in developing nations through the provision of critical capital that enhances productivity, reduces transaction costs, and stimulates private sector engagement (Barro, 2023). In Nigeria, government expenditure on infrastructure, particularly transportation, functions as a catalyst for endogenous growth by elevating total factor productivity, attracting private investment, and reinforcing regional economic integration (Oyesiku et al., 2023). This aligns with endogenous growth theory, which suggests that public capital investments yield increasing returns and sustained economic expansion, particularly in developing economies where technological advancement and human capital development are shaped by deliberate policy interventions (Romer, 2023; Mankiw et al., 2022).

Nigeria's public investment trends have historically mirrored its oil revenue cycles. The 1970s oil boom facilitated extensive infrastructure projects under the Third National Development Plan (1975–1980), including the Lagos-Ibadan Expressway and significant railway expansions. These initiatives contributed to an average annual GDP growth of 6–7%, accelerated rural-urban migration, and laid the foundation for industrial development in cities such as Kaduna and Port Harcourt (Ogbaro & Omotoso, 2017). However, the 1980s oil price decline and the implementation of the Structural Adjustment Program (SAP) in 1986 shifted fiscal priorities toward debt servicing, leading to severe reductions in maintenance expenditures and widespread infrastructure deterioration. By the 2023s, over 60% of federal roads had degraded, fostering a persistent pattern of deferred maintenance that continues to hinder economic efficiency (Ighodaro, 2020).

Focusing specifically on domestic public investment defined as federal government capital allocations to transportation projects, excluding external loans or foreign aid reveals transportation as a central component of Nigeria's development strategy. This sector encompasses an extensive road network of approximately 195,000 kilometers (with only about 60,000 kilometers paved), a railway system spanning roughly 3,500–3,800 kilometers (predominantly narrow-gauge Cape gauge), major seaports (including Lagos, Port Harcourt, and the Lekki Deep Sea Port), and aviation infrastructure. These elements collectively facilitate the movement of goods, services, and people, supporting key economic sectors such as agriculture (which employs approximately 35% of the workforce and contributes 23–25% to GDP), manufacturing, mining, and international trade (World Bank, 2024; African Development Bank, 2025).

Strategic domestic investment in transportation significantly reduces logistics costs currently estimated at up to 40% of final product prices, well above the global average of 10–15% enhances market access for farmers and small businesses, and mitigates post-harvest losses (Ali et al., 2015; NESG, 2024). Inadequate rural feeder roads contribute to spoilage rates as high as 40% for perishable goods such as tomatoes, yams, and grains, as documented by the Nigerian Stored Products Research Institute, while deteriorating transport infrastructure inflates food prices and constrains agricultural output (Agbigbe, 2016; Olabosinde, 2024). Empirical research confirms that public expenditure on transport and communication infrastructure yields significant positive effects on economic growth in Nigeria, generating immediate benefits through improved connectivity and long-term multipliers via enhanced trade and private sector efficiency (Babatunde, 2018; Chijioke & Amadi, 2020).

Nigeria, Africa's most populous nation with an estimated population of 238–242 million as of mid-2026 (Worldometer and UN projections), retains its position as the continent's largest economy, though nominal GDP stood at $188–252 billion in 2024 (World Bank and Trading Economics data). Persistent socio-economic challenges include youth unemployment rates of 5–6.5% (revised NBS/ILO metrics), inflation peaking at 34.6% in mid-2024 before stabilization, and poverty affecting 54–56% of the population (World Bank projections, 2024). These pressures are exacerbated by insufficient transportation infrastructure, which elevates transport costs (e.g., ₦2 million for a 20-ton truck journey from Maiduguri to Lagos in 2023) and exacerbates food price inflation (NESG, 2024).

From 2015 to 2025, domestic public investment under the Buhari and Tinubu administrations marked a resurgence in transportation sector development. Federal budget allocations increased from ₦80 billion (approximately 1.2% of the total budget) in 2015 to over ₦500 billion (roughly 2.5% of federal expenditure) in 2024. Notable projects include the 187-km Abuja-Kaduna standard-gauge rail line (completed in 2016), the 157-km Lagos-Ibadan standard-gauge rail (operationalized in 2021), full operations at Lekki Deep Sea Port (2023, handling over 287,000 TEUs in 2024 with a target of 500,000 TEUs in 2025), and the $13 billion Lagos-Calabar Coastal Highway (approved in 2024 as a public-private partnership, with Phase 1 segments under construction and partial openings anticipated by late 2025) (African Development Bank, 2025).

Supporting policy frameworks such as the Economic Recovery and Growth Plan (ERGP, 2017–2020) and the National Integrated Infrastructure Master Plan (NIIMP) have prioritized multimodal transport systems (road, rail, and maritime) to diminish excessive reliance on roads (which handle approximately 90% of freight) and improve logistical efficiency (Babatunde, 2018). Despite progress, funding shortfalls persist only 30% of NIIMP's $150 billion annual target has been met while corruption and administrative delays continue to impede full implementation (World Bank, 2024). The transportation sector's contribution to GDP remains modest at 2–3% (NBS data, 2024), below its potential of 4–5% as estimated by the African Development Bank (AfDB, 2025), underscoring the enduring infrastructure deficit projected at $2.3 trillion over the coming decades (AfDB, 2025).

This study evaluates the impact of domestic public investment on Nigeria's transportation sub-sectors road, rail, and maritime transport and their broader economic implications from 2012 to 2024. By analyzing federal capital allocations, policy interventions, and performance indicators, the research demonstrates how targeted investments can alleviate logistical constraints, enhance agricultural productivity, bolster non-oil exports, and advance inclusive growth in alignment with Nigeria's Agenda 2050 vision of sustainable prosperity (Oyesiku et al., 2013; African Development Bank, 2025).

1.2 Statement of the Problem

Nigeria's transportation sector continues to exhibit significant developmental deficiencies despite considerable governmental policy interventions implemented between 2015 and 2025. Approximately 40% of federal road networks remain in deteriorated condition, resulting in estimated annual economic losses surpassing ₦1 trillion due to operational delays, traffic accidents, and systemic inefficiencies. Rural regions, which accommodate approximately 50% of the national population, experience severe connectivity challenges that adversely affect agricultural productivity and food security, particularly concerning given the country's 2.5% annual population growth rate.

Urban centers such as Lagos and Abuja face chronic congestion issues, where logistics costs have inflated to approximately 20% of GDP – a figure that doubles global benchmarks – consequently discouraging manufacturing sector growth and foreign direct investment. The Buhari administration (2015–2023) emphasized infrastructural rehabilitation through its Economic Recovery and Growth Plan (ERGP) (2017–2020), prioritizing key projects including the Abuja–Kaduna and Lagos–Ibadan railway lines, alongside major roadway rehabilitations such as the Lagos–Ibadan Expressway. Subsequent policy continuity under the Tinubu administration (2023–present) has manifested through initiatives like the Lagos–Calabar Coastal Highway, a $13 billion public-private partnership, operationalization of Lekki Port, and adoption of the National Land Transport Policy in 2025.

While budgetary allocations for infrastructure development have increased substantially, evidenced by the ₦826.9 billion proposal for 2025, persistent structural challenges remain unresolved. These include chronic funding shortages, systemic corruption exemplified by the misappropriation of ₦200 billion between 2015 and 2023, implementation inefficiencies, and disproportionate reliance on road transport, which accounts for 90% of modal share. This over-dependence exacerbates cross-border smuggling activities, environmental degradation, and climate-related vulnerabilities. The absence of robust domestic public investment mechanisms continues to deter meaningful private sector participation, perpetuating low economic productivity, worsening youth unemployment rates, and deepening regional inequalities – factors that collectively heighten risks of sociopolitical instability.

1.3 Objectives of the Study

Aim: To investigate the effect of domestic public investment in the transportation sector on Nigeria's economy from 2012 to 2024.

Specific Objectives:

1. To examine the effect of domestic public investment on road transport.
2. To examine the effect of domestic public investment on railway transport.
3. To examine the effect of domestic public investment on sea transport.

1.4 Research Questions

1. What is the effect of domestic public investment on road transport in Nigeria?
2. What is the effect of domestic public investment on railway transport in Nigeria?
3. What is the effect of domestic public investment on sea transport in Nigeria?

1.5 Hypotheses

Null Hypotheses (H₀): H₀₁: There is no significant effect of domestic public investment on road transport in Nigeria. H₀₂: There is no significant effect of domestic public investment on railway transport in Nigeria. H₀₃: There is no significant effect of domestic public investment on sea transport in Nigeria.

1.6 Significance of the Study

This study contributes empirically to the discourse on domestic public investment in transportation and its economic impacts, offering substantive value across multiple domains. The findings hold particular relevance for economic planning and national development, as they elucidate the multiplier effects of transportation infrastructure on growth, trade diversification, and reduced oil dependency. By quantifying how strategic investments lower logistics costs and enhance productivity, the research supports sustainable GDP expansion, poverty reduction, and alignment with long-term development targets such as Agenda 2050 (e.g., per capita GDP of $33,000). World Bank estimates suggest potential gains of 2–3% in annual growth, alongside improved regional integration for inclusive prosperity.

For policymakers and government agencies, the study provides evidence-based analysis to optimize budgetary allocations across road, rail, and maritime infrastructure. It critically assesses past policies (ERGP, NIIMP) and current initiatives (coastal highway projects, port modernization), offering recommendations to mitigate funding shortfalls, corruption, and implementation inefficiencies thereby improving fiscal discipline amid budgetary constraints.

Academic and research communities benefit from the study’s contribution to literature on sub-sectoral impacts of public investment, particularly in Nigeria’s context. It advances endogenous growth theory applications and establishes a foundation for future econometric analyses (e.g., ARDL models) using 2012–2024 datasets, enriching infrastructure economics scholarship.

Educational institutions and students gain accessible material for curricula in economics, development studies, and public policy, fostering analytical rigor in understanding investment-growth dynamics while preparing graduates for careers in transport planning and governance.

The private sector and business stakeholders derive actionable insights on public-private partnership (PPP) opportunities, logistics optimization, and supply chain enhancements. Reduced infrastructure bottlenecks may lower operational costs, strengthen competitiveness, and attract foreign direct investment (FDI), particularly in manufacturing, trade, and e-commerce (projected 2024 revenues: $8.53 billion).

Rural communities and agricultural producers stand to benefit from the study’s emphasis on feeder road networks and market accessibility. Mitigating post-harvest losses (up to 40% for perishables) and lowering transport expenses could elevate farm incomes (35% of workforce), bolster food security, and strengthen rural-urban economic linkages for marginalized populations.

Finally, international development partners and agencies (e.g., World Bank, AfDB) may leverage the research to refine financing strategies for rail and port projects, aligning interventions with Sustainable Development Goals (SDGs) and poverty alleviation frameworks. The study underscores risk-return trade-offs in infrastructure financing, facilitating targeted support for sustainable growth partnerships.

1.7 Scope of the Study

The study is confined to the federal government's purview, with a specific emphasis on domestic public investment in the transportation sector, which includes capital expenditure allocations for roads, railways, and seaports, excluding foreign aid and loans. It analyzes trends in government expenditure and investment from 2012 to 2024, a period selected due to the availability of consistent data following economic rebasing and its alignment with relevant policy reforms such as the ERGP and post-2015 developmental initiatives. This temporal scope facilitates an examination of policy effects while recognizing spillover effects on adjacent sectors, notably agriculture and trade.