Refereed Journals

Emissions from vehicular traffic are one of the key drivers of urban environmental air pollution, degrading the ambient air quality in many African cities and across the globe. This study sought to assess the impact of traffic mobility measures on the emission levels of air pollutants from vehicle exhaust in Lagos, Nigeria. Traffic flow and vehicle mix were collected daily during morning, afternoon, and evening peak periods along selected arterial and two-lane collector roadways. Simultaneously, five (5) air pollutants from vehicular traffic emissions were observed at distinct monitoring stations along the roadways using portable gas detectors. The traffic flow and mobility measures were inputted into a multiple exponential model to estimate the concentration of each pollutant. The result of the vehicle fleet composition revealed 3.5%, 4.5%, 57%, 32%, 1.5%, and 2% for motorcycles, tricycles, personal cars, minibuses, large buses, and heavy goods vehicles, respectively, on the two-lane road and 10%, 35%, 27%, 10%, and 18% for motorcycles, personal cars, minibuses, large buses, and heavy goods vehicles, respectively, on the arterial. The results of a multiple exponential regression model (MER) showed significant contributions from traffic flow, speed, vehicle fleet proportion, and pollutant concentration (p <0.05). However, the impact on ambient air quality revealed severe pollution levels for CO and PM_2.5, while SO₂, NO₂, and PM₁₀ showed moderate, poor, and poor pollution levels. This study has provided evidence on how pollutant emissions increase rapidly during peak traffic conditions in heterogeneous traffic on different classes of roads and recommended policies for managing vehicle fleets and traffic congestion with the aim of reducing the impact on the ambient air quality and health of the public on heavily trafficked roadways in sub-Saharan African cities.

The perception and behavior of the public is key in reducing Traffic-related air pollution health burdens which has become an increasingly alarming problem in many cities across the globe. The study assessed the perception of the public about vehicle traffic emissions and the health hazard associated with them in Lagos, Nigeria using structured questionnaires. Multivariate statistical analysis and structural equation modeling were performed to determine the factors that were associated with the participant’s perception of traffic air pollution and the health risks it presents. The findings revealed the majority (78.9%) of the respondents were aware of the haze air pollution from vehicles and its adverse effects on health. The regression model showed a significant relationship between age, education status, employment status, road proximity, vehicle ownership and air pollution awareness (P < 0.05). However, the structural equation model SEM revealed that age, gender, marital status, education, employment status, and road proximity showed statistical significance (p < 0.05) and indicated a linear relationship to vehicular emissions perception. The findings suggest the need to increase public education for all ages and especially for roadside residents on the effects of prolonged exposure and long-term effects of transport-related air pollution and associated risk. The result is applicable in many developing cities, especially in Sub-Saharan Africa.

Asphalt pavement temperature has several applications, including pavement structural design and evaluation, asphalt mixture design, asphalt binder grade determination and material aging characterization. However, available asphalt pavement temperature prediction models were mostly developed for temperate climatic conditions. Before such models are adopted for use in a tropical climate to facilitate advanced pavement engineering, their applicability must be verified. This study evaluated five empirical asphalt pavement temperature prediction models: the Lukanen (BELLS 3), Park, Diefenderfer, and Taamneh models, all developed in the United States, and the Asefzadeh model, formulated in Canada, to ascertain their prediction accuracy in a tropical climate, using the West African country Ghana as a case study. The results of such a model evaluation study will justify the adoption of existing models for local application or the development of new ones suitable for tropical climates. In this study, in situ asphalt pavement temperature data were measured at two sites for eight months: Kumasi and Tamale in the Forest and Savannah climatic zones, respectively. The measured pavement temperature data were compared with predicted pavement temperatures using the two independent-samples t-test, the coefficient of determination, the line of equality, and three error statistics (mean bias error, mean percentage error and root mean square error). It was found that the Park model provided a more accurate pavement temperature prediction in both climatic zones. The other models either over-predicted or under-predicted asphalt pavement temperature with significant error margins. However, there is a need to improve the prediction accuracy of the Park model as considerable over-prediction occurred at a temperature of at least 47 °C or a local model developed.

In Sub-Saharan Africa, vulnerable road users make up approximately 50% of all traffic fatalities. Despite the dangers of using motorcycles for transportation, the usage of motorcycles—and more recently, motor tricycles—for both personal and commercial purposes has increased exponentially in most Sub-Saharan African cities. The study sought to study the safety, health and environmental impact of commercial motorcycles in Sub-Saharan African cities. Two cities—the national capital and a secondary city—were selected in each of our five study countries: Ghana, Liberia, Kenya, Tanzania and Uganda. Using a mixed-methods approach, motorcycle taxi operators were surveyed and key transport stakeholders were interviewed in these ten cities. In Ghana, where both motorcycle and motor-tricycle taxis are officially banned but continue to operate, we also surveyed motor-tricycle taxi operators. The results indicated variability in accident occurrence across countries for both minor and major road traffic collisions (RTCs) among motorcycle/tricycle taxi riders. Apart from Liberia, motorcycle/tricycle taxi unions in our study countries contribute to improving the safety of their riders. Interest in electric bikes is low amongst riders in all five countries, with education and infrastructure provision required to cause a shift from conventional bikes to electric bikes.