The integration of cloud software into safety-critical railway applications introduces new challenges in ensuring availability and reliability. Traditional modeling techniques may not adequately capture the distinction between safety-critical and non-safety-critical software components in cloud-based architectures. This research explores the integration of safety criticality into Petri net modeling for availability analysis of cloud-based railway applications. Two Petri net models are developed and compared: a traditional non-colored model and an advanced colored model that explicitly represents the safety-critical aspects. The comparative analysis quantifies the differences in availability and reliability metrics between the two modeling approaches. The findings demonstrate the importance of integrating safety criticality, as the colored Petri net model provides more accurate insights into the availability of safety-critical components. The results contribute to the knowledge on availability modeling for cloud-based railway systems and provide practical implications for designing and maintaining these critical infrastructures to meet safety and reliability requirements.