Dar es Salaam’s Bus-Rapid-Transit system in view of systemic criticality

• Transit systems contribute to improved mobility and socioeconomic growth in Africa. • Design and location of transit system matter how exposed it is to hazards. • Informal transport systems are resilient compared to centralized transit systems. • Centralized transit systems showcase increased vulnerability and systemic risk. • Protecting improved informal systems reduces dependency in a standalone system. The Dar es Salaam Bus Rapid Transit (DBRT) system is a cornerstone of urban mobility and socioeconomic development. However, its fixed-route, centralized design makes it highly vulnerable to flood-related disruptions, a risk exacerbated by climate change, unplanned urban development, and the loss of green spaces. Using DBRT, as case study this paper assesses systemic criticality of a transport system through surveys, key-informant interviews, participatory scenario workshops, and secondary research. The findings reveal profound logical and physical interdependencies between the DBRT and key economic sectors; a disruption could therefore cascade through critical infrastructures vital to the regional socioeconomic systems. To mitigate these risks, the study recommends integrating disaster risk management into transit planning, formalizing informal transportation for redundancy, and promoting nature-based solutions, such as recuperating wetland and green covers, to buffer against flooding and sea-level raise. Long-term strategies should pursue polycentric urban design to decrease reliance on centralized infrastructure. This study underscores the necessity of systemic criticality assessments for building resilient transit systems in rapidly growing cities.