The integration of Information and Communication Technologies (ICT) has become essential to enhancing urban infrastructure and addressing challenges in modern cities, particularly in urban mobility. Bus Rapid Transit (BRT) systems are crucial for enhancing mobility, but they require robust monitoring to ensure safety and service quality, particularly at high-traffic stations. This paper presents a hierarchical availability model for monitoring systems in BRT stations, combining Reliability Block Diagrams (RBDs) to represent the system structure and Continuous-Time Markov Chains (CTMCs) to model the dynamic behavior of Edge Computing components. The proposed approach supports the evaluation of system availability and informs decision-making in the design and planning of smart urban infrastructure. A case study demonstrates the model’s applicability in a realistic IoT-enabled BRT environment, highlighting its effectiveness in estimating availability metrics and improving service resilience. Evaluation results indicated a baseline system availability of 99.70%, translating to nearly 26 h of annual downtime. Sensitivity analysis revealed the Edge computing unit as the most critical component, and implementing warm standby redundancy for this unit substantially improved system availability, reducing annual downtime by up to 76% in evaluated scenarios.