Intercontinental rail freight transport has made significant strides in recent years, demonstrating its potential as a critical player in the global supply chain, such as Eurasian rail freight transport. However, Eurasian rail freight transport encounters challenges, including the presence of multiple rail systems with varying railway gauges, and especially in addressing the diverse requirements of the modern global supply chain. The traditional ’one service for all’ operational strategy is incapable of meeting the diverse transport requirements, emphasizing the need for more tailored solutions. We propose a time-space formulated Intercontinental Scheduled Service Network Design (I-SSND) for a relay intercontinental rail freight transport system, which necessitates an extension of the Scheduled Service Network Design (SSND). The I-SSND model, as a practical management tool, aims to move away from the traditional ’China-Europe Block Train’ business model, which offers only standard service, by enabling service differentiation. I-SSND model consider border crossing terminal times as well as train length variability across multiple different rail systems. It allows different orders from different origins to be consolidated at borders and share the same train service for the main transit based on their individual time constraints. The I-SSND model can assess demand variability and potential disruptions in the Eurasian rail network, including extended border crossing times, and evaluate their impact on overall network performance. The initial application of this model in Eurasian rail freight transport has yielded encouraging results. Mixed services demonstrate better performance compared to single standard services; the analysis shows an increase in profit growth and accepted orders. However, uneven demand distribution reduces overall network throughput and poses challenges for efficient capacity utilization, especially when compared to a more evenly distributed demand. Additionally, by integrating delay tolerance in mixed services, various metrics have significantly improved. On average, container acceptance increased by 10.44% and profits by 37.26%. These findings provide actionable managerial insights for intercontinental rail freight and highlight the necessity of establishing an entity to coordinate rail capacity planning across the various national rail networks involved.