BIM methodology early in the design phase must be coordinated and developed in cooperation between the designers and project engineers from the contractor. The amount of information must be agreed on so that during the construction stage the workers and staff will be capable to successfully use and analyze data from the digital interpretation of the structure.

In order to achieve that, we can create user-defined attributes (UDA). Attributes are associated with all objects in a BIM model and the program that was used to model the object automatically predefined some of the attributes. Objects can also be enriched with project-specific UDA as shown in the table below.

One of the most important parts of constructing a high-quality BIM model is adding useful attributes to objects in the model. The more structured data is added, the easier it is to use the model at later stages. On the downside, a large set of attributes is hard and laborious to maintain. The key is understanding what kind of information is useful at different life-stages of the BIM model. In an IFC-viewer like Solibri, these attributes are shown when marking an object. For the Randselva Bridge project, the user-defined attributes are shown in the custom-made curtain “A_E16_PART_INFO” seen in the below figure.

Figure - a screenshot from Solibri. The custom-made curtain “A_E16_PART_INFO” shows the UDAs added for a column part of the Randselva Bridge

In the project, one of the most used UDA was “construction sequence“. This attribute states which cast unit the object belongs to. This enabled the contractor PNC Norge to plan their orders of concrete, reinforcement and post-tensioning in a better way, making logistics at the site easier.

The figure below shows the BIM simulation of the first two-deck segments in Axis 3. As the BIM model moved through its life stages, the type of user-defined attributes needed for an object will most likely change due to revised requirements. Changing user-defined attributes for objects in the BIM model is relatively easy.

Figure: Using UDAs (user defined attributes) to show different construction sequences (Axis 3: segments 01 and segments 02 phases)