JCBM (2020) 4(1). 24-33 Environmental and Socio-Economic Impacts of Ojodu-Berger Road Upgrade, Lagos, Nigeria W.A. Alade 1 1 Department of Urban and Regional Planning, University of Lagos, Lagos, Nigeria Received 14 june 2019; received in revised form 1 October 2019 and 12 December 2019; accepted 20 December 2019. https://doi.org/10.15641/jcbm.4.1.785 Abstract Extensive road project in large cities produces diverse impacts. This study attempts an assessment of the environmental and socio-economic effects of a recent road upgrade, the mitigating measures of adverse effects experienced and their effectiveness in Ojodu Berger community, a major transport node in Lagos, southwestern Nigeria. Using a survey research design through questionnaire administration, 120 respondents comprising of 50 residents, 40 traders and 30 transport operators were sampled using the purposive sampling technique. The Relative Significance Index (RSI) of project impacts was measured using 27 variables as identified in the literature and general observation of situations in the project environment before the survey. On a 5-point Likert scale at the pre-construction, construction and post-construction phase of the project. The study reveals poor environmental conditions at the pre-construction phase, which became escalated in the construction phase; noise pollution is the most significant impact (RSI = 4.36). At the post-construction phase, encroachment on pedestrian facilities is the most significant impact (RSI = 4.20). Socio-economic impacts such as increased rental value, unemployment and displacement of businesses were also significant. The Mean Index (MI) of 3.14 for the construction phase impacts was the highest compared to 3.00 at the pre-construction phase and 3.02 at the post-construction phase. Mitigating measures against adverse impacts were both effective and ineffective, while some adverse impacts were not mitigated. There was no clear evidence that an impact study was done before project implementation. The study recommended strong government commitment to environmental and social impacts assessment of road development, more robust stakeholders' engagement for the formulation of strategies and measures to address the adverse impacts of similar projects in the future. Keywords: Construction, Environmental, Impacts, Social, Upgrade. 1. Introduction The expansion and provision of road infrastructure around the world have been unprecedented in the last two decades (Alamgir et al., 2018). Since 2000, the length of official roads has increased by 12 million kilometres worldwide, and it is expected that there will be a further increase of about 25 million kilometres to be built by the year 2050 (Dulac, 2013). This massive expansion in road infrastructure provision can be attributed to governments' set vision to make public, economic and social services physically more accessible to all the people in the rural and urban areas around the world (ERA, 2012; Arethun and Bhatta, 2012). Provision of access routes has higher potentials for far-reaching implications on the bio-physio- chemical and socio-economic environment of the host 1 Corresponding Author. Email address: aalade@unilag.edu.ng community as well as the living conditions of dwellers (Soneye, 2007). Around 90% of all new infrastructure projects are occurring or expected to occur in developing nations of the world (Dulac, 2013). In Africa, the 35 major 'development corridors' being planned or currently in progress would crisscross the continent, collectively exceeding 53,000 km in length (Laurance et al., 2015). Roads that are effectively located and constructed can provide positive outcomes for economic growth and social integration, and access to larger urban markets for local producers (Bryceson et al., 2008). On the contrary, roads that are poorly planned or executed can create numerous environmental (Lawrence et al., 2015), economic (Collier et al., 2015), and socio-political problems (Bambach and Mitchell, 2015). For example, a University of Cape Town Journal of Construction Business and Management http://journals.uct.ac.za/index.php/jcbm