Public transport is arguably considered the backbone of today’s urban mobility ecosystem and is generally regarded as an important element of the sustainable mobility paradigm. As systems, they comprise vast societal investment owing to the infrastructures and operations required to provide the designated service. As projects, public transport systems have financial, societal, and environmental impacts that ought to be assessed through the scope of sustainability. Through sustainability, future generations’ financial, societal, and environmental needs are not compromised to meet the present generation’s needs. Thus, sustainability assessments can assist decision makers in perceiving the impacts and implications of an existing or under-consideration system on society and deciding on corrective actions. For the case of public transport systems, such assessments can assist in evaluating the expenditure distribution of the system and suggest actions that could maximize welfare gains under financial, social, and environmental criteria. Within this scope, the current paper proposes a methodological framework for unraveling transport systems’ sustainability to reveal their spatiotemporal dependencies. The study proposes a cost–benefit analysis framework where a public transport system is segmented and assessed into three levels: stops, lines, and administrative areas. Stop and line levels incorporate essential characteristics allowing their independent evaluation. The assessment of administrative areas aggregates characteristics from previous levels, spatially distributing the public transport system’s evaluation. By incorporating additional sociodemographic data, the administrative area level’s assessment links the evaluated transport system to societal characteristics, enhancing the decision maker’s perspective. The framework is showcased with Nicosia’s public bus transport system.