This article investigates the wider impacts of community severance associated with road infrastructure development in Nairobi (Kenya), and how the impacted local community responds and/or adapts to such changes. Today, Nairobi is experiencing significant stress due to inadequate transport and infrastructure services, with consequent challenges linked to increasing traffic congestion, road safety issues and transport-related pollution. The study uses an explanatory sequential mixed-method approach comprising a survey with 452 households, six focus groups and a community engagement workshop, to explore the impacts of the development of the Missing Link# 12 bypass passing through the informal settlement of Kibera. The results indicate that the development has caused social issues linked to evictions and displacements, creating a divisive effect within Kibera, impacting the community's social inclusion and interaction. Concerns about health due to the environmental risks of increased exposure and vulnerability to air and noise pollution also emerged strongly. The case of Missing Link# 12 highlights the need in African cities for the formalisation of participatory mechanisms in transport infrastructure development. This way planners and decision-makers would be able to take into account the mobility needs and impacts upon more vulnerable groups of users, beyond solely increasing traffic capacity.