Road ecology and transport planning assessment in Nigeria: evidence, challenges, policy gaps, and pathways to nature-positive linear infrastructure development

Rapid expansion of transport infrastructure in Nigeria is reshaping ecologically sensitive landscapes, including the Lower Guinean–Congo forests, Niger Delta wetlands, freshwater systems, and protected area complexes. Although roads support economic growth and mobility, their ecological externalities – habitat degradation and connectivity loss, wildlife mortality, hydrological alteration, pollution pathways, invasive species pathways, and human-access dynamics – remain insufficiently integrated into planning assessment and decision‑making. We review and synthesise Nigeria‑specific road ecology studies to characterise the scale, mechanisms, and impacts of transport development, and to identify emerging risks alongside technical and policy improvements. The paper, among other thematic analyses, evaluates environmental governance framework in Nigeria, particularly the Environmental Impact Assessment Act and National Environmental Standards and Regulations Enforcement Agency regulations, revealing systemic weaknesses in enforcement, early‑stage project decision‑making for biodiversity‑sensitive areas, cumulative impact assessment, and post‑construction monitoring. In response to the identified issues, we propose actionable reforms to mainstream conservation‑sensitive infrastructure development, including institutionalising Strategic Environmental Assessment, embedding connectivity mapping in route selection, mandating wildlife crossings and hydrologically adaptive designs, and establishing a national roadkill monitoring programme. We conclude that integrated road ecology research, strengthened regulatory capacity, and cross‑sectoral planning are essential to safeguarding Nigeria’s fragile ecosystems amid accelerating transport network expansion.