This paper presents results from an ongoing project named “Safety Assessment Framework for Efficient Transport” (SafeT) led by Bane NOR. Bane NOR is the government agency that owns, operates and develops the Norwegian railway infrastructure. The main objective of the SafeT framework is to offer a systematic, reusable way for creating system wide conceptual design models, and based on them, creating a common risk model, which in turn will facilitate the safety assessment, requirements specification and safety demonstration of the system under consideration. Previously reported results from SafeT include evaluation on the role of models and evaluation of hazard identification approaches to establish how models can be used throughout the life cycle of a system in a manner that facilitates the overall safety demonstration and assessment. This paper specifically addresses the safety assurance part of the framework, or more precisely evaluates how different safety assurance approaches support safety argumentation. Since SafeT focuses on model-based approaches and the conceptualisation phase, our scope is limited to approaches supporting model-based engineering in the early stages of the system life cycle. The evaluation considers to which degree common safety techniques support safety argumentation, meaning the potential to produce the models and descriptions necessary to substantiate the different claims that need to be made in a safety argumentation. The results are included in the SafeT framework as support for users in selecting appropriate development approaches supporting safety argumentation. A case study on the conceptualisation of a railway system for securing work areas is used to exemplify the SafeT framework.