21 Jul Exchanging Civil Infrastructure Design IFC data
Industry Foundation Classes (IFCs), developed by buildingSMART, are a neutral and open specification for Building Information Models (BIM). IFC-compliant applications can import and export design model information as IFC files and share or make use of data created in other IFC-compliant applications.
All software vendors have equal access to the specifications of the IFC data model and it has become a widely adopted format which facilitates interoperability and enables a collaborative BIM process.
IFC Geometry
IFC encodes both geometry and semantic data. This means that in addition to robust geometry including vectors, solids, surfaces and collections of geometry (like groups and symbols), IFC can encode spatial and relational data associated with each object. When the geometry of a model is identified as an infrastructure or building element for example, it gains meaning within the context of the project and is known as a ‘semantic object’. Its semantic capacity makes IFC an ideal file format to share a 3D model within a building information model.
IFC files exchanged within a project workflow can contain enough information for a standard BIM viewer to display 3D model representations of a project’s objects, including their associated properties and quantities. The screen shows a road design, as exported from Civil Designer Software, with additional associated information as displayed in the Solibri BIM viewer.
Customising IFC Data
Civil Designer allows shared IFC data to be customised according to the requirements of the recipient. Prior to export the engineer can set up custom IFC files, assigning the appropriate northern or southern coordinate system and specifying the extents of the shared data. Data can be allocated to a single, or multiple IFC files, and may incorporate all or a selection of the proposed infrastructure services associated with the project.
A shared road design model, for example, may consist of an entire road, road segments or multiple roads. In addition, it may include road layerworks and other parameters as required (see dialog ).
IFC File Management
File compatibility within a data rich format provides an essential step in addressing the inefficiencies of a distributed and fragmented industry. Effective BIM processes, however, must also rely on coordinated workflow. This may be controlled by using a BIM platform that allows specific tasks to be assigned to project members during the design phases.
IFC files (and other files) that are contributed by project stakeholders over a project’s lifecycle need to conform to an agreed naming convention to facilitate the coordination process. The BS1192 BIM naming standard, for example, provides for the following fields which can be defined in a file name:
Project, Originator, Zone/System, Level, Document type, Role, Document number, Suitability status, Revision number and Document description.
According to the convention the fields must be separated by dashes (-) to create the BIM standard name, for example: “Project01-KNB-Z1-L1-DR-C-0600-S0-P01-Tutor.IFC”.
Naming shared files according to their BIM zone, purpose, permissions, and revision introduces further value to their contribution within a project’s workflow. Exchanging project information using the IFC format in this way contributes to the efficiency of a project’s development and assigns ownership to the various project contributions.
Further benefits associated with adopting the IFC format data for data exchange within a project’s workflow include portability, accessibility of project information from different applications, the extensibility of the IFC file format and the fact that a project remains independent of limitations of versioning found in proprietary file formats.
Henk van der Watt, Civil Technologist at Harrison Grierson in New Zealand, and previously at NWE Consulting, has used Civil Designer for a number of large scale infrastructure design projects. He explains that “the design model is the project reference of the future. Workflow efficiency depends on design integrity so that accurate information can be extracted from the design model rather than from separate quantity and management documents”