Construction process simulation and IFC based BIM for tunnel projects

The construction industry is struggling with stagnating productivity, projects are often delivered late and over budget. A remedy is the use of Building Information Modelling (BIM). While BIM is widely used in building construction, its application in underground construction, especially in tunnelling, is lagging behind. One of the numerous BIM use cases is the construction process simulation also known as 4D simulation, which significantly supports the planning and execution phases of projects. However, the use of construction process simulations in the construction industry is rare due to their complex creation process.
The goal of this master thesis was the development of a strategy to facilitate the creation of construction process simulations for tunnel projects and to integrate the time-related information in the IFC schema in order to get a 4D BIM model.
Contrary to the current process of developing 4D simulations, where the discrepancy between the element breakdown structure (EBS) of the BIM model and the work breakdown structure (WBS) of the schedule is leading to considerable time and effort being spent on linking BIM model components and schedule activities, the proposed concept suggests, for tunnel projects, to develop the schedule out of the BIM model. Each model element should have one single schedule task. This idea of setting WBS equal to EBS is reasonable and legitimate, as tunnel projects are linear construction sites. By maintaining the global unique identifiers (GUID), when developing the tasks out of the model elements, linking schedule and model can easily be done though matching GUIDs.
Inserting time-related information into the BIM model through the IFC schema in order to create a 4D BIM model allows more in-depth planning. Knowing for example the excavation volume over time helps in planning the amount of trucks needed. Also, presenting planned expenses over the project’s duration helps facilitate an earned value analysis. The 4D BIM model provides these planning services and the overall goal of having a single source of truth is enforced.
For the purpose of validation, the proposed strategy was implemented on ILF’s (Zürich) tunnel project “Brüttener Tunnel”. Results show that the proposed strategy is useful, and simulations can be created with only little effort. The expected impact of this work is an increase use of 4D simulations during the planning and the execution phase. The use of construction process simulations will help the construction industry to improve their productivity and meet project targets in terms of time and money.