BIM for Architects: The case of Siltasairaala

Bridge Hospital is the largest construction project in the history of HUS (the Hospital District of Helsinki and the Uusimaa region of Finland). The project is an extension to an existing hospital complex and is located in a very tight site in the Meilahti neighbourhood of Helsinki. The name is derived from a bridge-like part that connects the ward and the hot hospital building to another with daytime clinical consultation facilities. The completed building will encompass roughly 70.000 square meters of built area. Construction is due to be finished next year, 2022. Building information modelling (BIM) of this project received international recognition when we secured the best public project award in the Tekla BIM Awards 2020. In this blog post, I will roughly outline the BIM process and reflect on some aspects that could be improved in the future.

Architectural design of the bridge hospital is a joint venture between four architectural offices in different physical locations. While currently, remote working is the norm after one year of covid-19 restrictions, it was not the case when this project started. Back then, it was a very new way of working for most participants. The conceptual design of the building did not facilitate division into equal parts. So, we had to invent working methods that would allow multiple team members to work on one, shared project from different locations.

The key, to achieving positive results from modelling, is to set realistic targets early in the project and to reach a collective agreement on the set targets, together with all the different design teams.

Modelling was a client requirement and it’s an integral part of the architectural responsibilities in the bigger construction projects in Finland nowadays. Usually though, the definition for the requirement is quite vague and leaves a lot of room for discussion within the project. The key, to achieving positive results from modelling, is to set realistic targets early in the project and to reach a collective agreement on the set targets, together with all the different design teams. From a designer’s perspective, it’s necessary to define these qualities in advance because they, often, have implications on how the model is being built.

Siltasairaala - View from the courtyard © Team Integrated

BIM coordination was included in the list of tasks of the principal designer and was thus carried out by the joint venture of architects. As is customary in BIM projects, we created a BIM project execution plan for the Bridge Hospital. It was done in co-operation with all the consultants and the client before extensive modelling. Some modelling had already been done when the plan was finalized. While the planning could’ve been done earlier, it wasn’t a critical issue, as all parties were able and willing, to adjust their modelling according to what we agreed on.

Within the BIM execution plan, we specified the use cases for all models, at different stages of the project. The value of the plan is that it describes the contents and objectives of the models collectively.

With the plan everyone can try to understand the needs of the other stakeholders and grasp what their own model is being used for. Also, it makes visible to everyone what is expected of the models and at which stage. Documented model contents, additionally, allow verification of the models and their information content even by a third party that is not actively involved in the project.

Siltasairaala models were used extensively throughout the whole design and construction process. Within the different design disciplines, they served as the primary source for quantity estimates and scheduling. Even when the final document was a traditional static spreadsheet, the contents were mostly generated from the models. A lot of the information was also stored in the exported IFC models and this enabled the team at the construction site to get quantities relevant to the current situation. They were also able to set limits that displayed only what is necessary at a given time or in a certain area of the building.

Information and data management

From early sketching stages, immediately after the competition phase, to the construction site, virtual models have played an important role, both in the coordination of all disciplines and in the visualization of design solutions to everyone involved. Smart and efficient information management has been essential, as the federated model consists of roughly 200 sub-models from 20 different disciplines. Due to the sheer size of the project, all model checking had to be done in reasonably sized parts. It is necessary to be aware of the project phase and the status of modelling when working with the models. Here, the BIM execution plan comes in handy, as it outlines the main milestones and the contents of the model at different stages of the project.

Smart and efficient information management has been essential, as the federated model consists of roughly 200 sub-models from 20 different disciplines.

IFC files were used for information exchange between disciplines. As design software solutions usually generate all sorts of data fields in the files, it’s critical that the important fields have been documented by the designers. In the Bridge Hospital project, each consultant, who produced a model also prepared a document, which described the fields that are being used. This approach facilitated automated model checking. Knowledge of what information is stored in the models and where exactly to find it, is crucial in enhancing the use of models in projects.

Longitudinal section through the building. © Janne Kivelä/Team Integrated

Early on, in the process, we agreed with all the participating teams that we would try to push the boundaries of modelling through this project. All building service systems were comprehensively modelled including UI terminals, electric outlets and furniture. Following this, the architectural model was augmented with MEP and structural models as reference. This process made it possible to generate individual room charts almost directly from the models. While the process was tedious, the result is quite impressive and the models have proven to be very efficient in generating the required data quickly.

All building service systems were comprehensively modelled including UI terminals, electric outlets and furniture.

Interior view from the Virtual reality model © Douglas Triana/Team Integrated

The Architectural model was used as the basis for indoor work schedules. The production and design of precast concrete and steel structures benefitted heavily from the modelling done by the Structural team. Production schedule management and reporting were done with model-based tools that were directly linked to the design software. A constantly updated mobile model, has been helping workers on site with daily tasks. This version consists of not only the design models but was also enriched with 2D drawings.

BIM from an architect’s perspective

Even though, the use of models is increasing in the construction industry, traditional two-dimensional drawings remain the primary document on the construction site. Such was the case in this project as well. This necessitates the maintenance of a lot of information simultaneously in multiple drawings and files. Thus, persistent information management is pivotal to handling data consistently across the whole project. An additional challenge of a joint venture was that we didn’t have any standardized ways of working together. On the brighter side, we could source the best practices from all the four architectural offices involved in the project. It was generally more challenging, to introduce new people to the project, when the ways of working differed from all the other projects in the office. Working as a large team required rigorous documentation and consistent communication regarding all the information that was being used and how it was stored. Luckily, modern instant messenger solutions made this kind of communication, rather easy.

Data field content-based color-coding of objects (for example, based on their surface materials, types) facilitates easy visual checks and enables the quick spotting of outliers.

So how did we keep the information coordinated and what methods did we use to verify information content of the building components? Often, the most efficient way of validating data was inside our design software as it enables quicker corrections. Data field content-based color-coding of objects (for example, based on their surface materials, types) facilitates easy visual checks and enables the quick spotting of outliers. An added benefit of this method is that these diagrams also provided different kinds of data visualizations for the team at the construction site.

In many cases, data also consists of different requirements. For example, certain fire or acoustic requirements need very precise door specifications. As all this data is stored within the model, it’s possible to check and rule out mismatches, if any. Within the design software this is done primarily using schedules. Our approach was that visual checking and comparisons were, as much as possible, done within our design software. Software-based model checking tools were used for quality assurance in the architectural models. Examples include checking door and window fire ratings against the walls they are placed in or checking opening clearance of windows. Software checks allow processing of large data quantities consistently across a huge building. There’s a whole variety of rule templates available and often the problem seems to be figuring out what to check.

Models in client workshops

The client desired the involvement of future users of the building, as much as possible, in the design process. Intricate BIM Models were a huge step forward in meeting that goal as they facilitated the generation of virtual models without much additional workload. Virtual models were presented to the users in CAVE (Cave Automatic Virtual Environment). This technology presented the design in a more easily perceivable form than traditional drawings. To avoid misunderstandings, it is necessary to communicate the current design phase in the virtual models as well. For example, early on, the models included very suggestive material definitions only. At this stage, the central aim was to assess the spatial qualities. Later, these definitions became more refined and started to reflect final material palettes. Evaluative options for design alternatives were sometimes included in the virtual models. This facilitated more informed decisions, but also led to increased workload as separate models had to be produced.

CAVE Workshop with the users © Team Integrated

Evaluative options for design alternatives were sometimes included in the virtual models.

A building of this size couldn’t have been managed as well without the aid of BIM. Managing the properties of some 3,5k rooms and literally millions of building components, would have been laborious, without the benefits of automated checking and the assistance of information management tools that were used in this project. Still, there’s a lot of room for improvement regarding the scope of these tools.

Often the scale and complexity of such a project opens a lot of opportunities to improve the methods of working, but there’s still a lot of resistance in trying new methods. This can partly be attributed to the fact that you still need to produce all the traditional documents too. There were many instances in this project, when we were surprised by how the data produced by us had been used by other consultants. There is a lot of potential for more extensive use of BIM models. Luckily, the attitudes toward open data sharing have improved and this leads us to new possibilities.

Author: Janne Kivelä