icccbe 2010 © Nottingham University Press Proceedings of the International Conference on Computing in Civil and Building Engineering W Tizani (Editor) Abstract Virtual organisations in construction are very dynamic in their composition and operability. In this paper we describe an approach for the realisation of context-aware access management, mapping the required dynamic VO behaviour in an ICT environment with the help of a generic platform ontology describing the actors, resources and processes of a VO and enabling personalised context-specific user support complemented with role-based business, access and representation profiles. To demonstrate and verify the benefits of the suggested approach a set of services for cross-organisational defect management have been implemented. For this specific sub-area of construction the developed ontol- ogy has been extended to store metadata on defect records for tracking and corresponding media data (photos, memos, videos etc.) for the documentation of found defects. By combining the RBAC and ABAC models the developed platform ontology provides for creation of context-aware access permis- sions to control service access, information access and data representation using flexible access rules. Reported is research undertaken in the frames of the German BauVOGrid project performed by 3 academic and 6 industry partners (2007-2010). Keywords: role-based information access, RBAC, ABAC, context-awareness, ontology 1 Problem statement Construction is a project-based industry. Each construction project can be considered unique because the product, the environment, the partners and the techniques used differ heavily from one project to another. Although construction projects are executed with fixed and agreed plans, external conditions cause more dynamic changes than in other industries. In a production period of several months or even years the parties involved or the agreed product may change under various circumstances. This dynamicity necessitates flexible cooperation of the participating organisations, joining their efforts for the duration of a project into a so called virtual organisation (VO), and therefore requires an approp- riate cross-company ICT solution. Typically, information processing in a VO takes place on a virtual platform which organises the access of the VO members (subjects) to the digital information resources (objects). To ensure that the subjects receive the necessary permissions for their work on the objects, the role-based access control model (RBAC) has been established in the last years (Hine et al. 2000; Ferraiolo et al., 2007). This standardised access model is based on the concept of user role as an intermediary between subjects and permissions. Accordingly, in the initiation of a VO roles are assigned to permissions, and re- corded in a VO model. These roles, which correspond to actual positions in a corporate hierarchy, are then assigned to users that later acquire the associated permissions. RBAC is thus more scalable than Dynamic context-aware information access in virtual organizations Frank Hilbert, Peter Katranuschkov & Raimar J. Scherer Institute of Construction Informatics, Dresden University of Technology, Germany