CARBON EMISSION MODELING OF URBAN ROAD NETWORKS: EVALUATING GREEN TRANSPORT STRATEGIES THROUGH MICROSIMULATION IN NIGERIA

Urban transport systems in developing countries are increasingly recognized as major contributors to
greenhouse gas (GHG) emissions and urban air pollution. In Nigeria, where rapid urbanization and motorization
have outpaced the growth of sustainable transport infrastructure, road traffic emissions constitute a significant
share of total carbon output. Lagos, Abuja, Port Harcourt, and other major cities experience chronic congestion,
excessive fuel consumption, and high vehicular emissions. While several studies have assessed traffic
congestion and mobility challenges, there is limited application of microsimulation-based emission modeling to
quantify the effectiveness of green transport strategies in Nigerian contexts. This study develops a
microsimulation framework to model carbon emissions from selected urban road networks, using SUMO
integrated with COPERT/HBEFA emission factors calibrated for Nigeria’s vehicle fleet. Traffic and emission
data were collected from Lagos’s Ikorodu corridor, characterized by mixed traffic conditions including private
cars, minibuses (Danfo), motorcycles (Okada), and heavy-duty trucks. A baseline emission scenario was
developed, and alternative green transport strategies were evaluated: (i) traffic signal optimization, (ii)
introduction of dedicated bus rapid transit (BRT) lanes, (iii) vehicle restriction (odd–even license plate scheme),
and (iv) eco-driving enforcement. Results show that baseline conditions generate high per-kilometer emissions
due to stop-and-go traffic, vehicle idling, and old vehicle technologies. Traffic signal optimization reduced
carbon dioxide emissions by 12%, while BRT priority lanes achieved up to 22% reduction by shifting demand
toward high-occupancy vehicles. Odd–even restrictions achieved short-term emission reductions (18%) but
raised concerns about equity and long-term sustainability. Eco-driving yielded modest reductions (8%), but
could scale with digital enforcement. The study concludes that integrated strategies—particularly mass transit
prioritization combined with intelligent traffic management—offer the most viable pathway to reduce transportrelated emissions in Nigerian cities. The findings provide empirical evidence to guide policymakers in aligning
Nigeria’s transport sector with sustainable urban mobility and climate change mitigation commitments under the
Paris Agreement.