Abstract. Building information modelling (BIM) is defined as a process involving the generation and management of digital representation of physical and functional characteristics of a facility. The purpose of interoperability in integrated or "open" BIM is to facilitate the information exchange between different digital systems, models and tools. There has been effort towards data interoperability with development of open source standards and objectoriented models, such as industry foundation classes (IFC) for vertical infrastructure. However, the lack of open data standards for the information exchange for horizontal infrastructure limits the adoption and effectiveness of integrated BIM. The paper outlines two interoperability issues for construction of rail infrastructure. The issues are presented in two case study reports, one from Australia and one from Malaysia. The each case study includes: a description of the project, the application of BIM in the project, a discussion of the promised BIM interoperability solution plus the identification of the unresolved lack of interoperability for horizontal infrastructure project management. The Moreton Bay Rail project in Australia introduces general software interoperability issues. The Light Rail Extension project in Kuala Lumpur outlines an example of the integration problems related to two different location data structures. The paper highlights how the continuing lack of data interoperability limits utilisation of integrated BIM for horizontal infrastructure rail projects.