The large-scale renovation of the Binnenhof (the Dutch houses of parliament) in The Hague has barely started, but digitally the 400-metre long building site fence has already been erected. Thanks to an innovative 3D model, the building process is clear to everyone involved in the project. That creates clarity, say Bauke van der Goot and Thomas Smits.
The fish stall, the statue of Willem II and even the overhead tram wires: in preparation for the renovation of the Binnenhof, even the smallest details in the immediate vicinity of the Binnenhof have been incorporated in a 3D model that is part of the Building Information Model, or BIM for short. In the Google Maps-like virtual environment that BIM specialist Thomas Smits shows on his computer, you can walk alongside the site fence to the Stadhouderspoort to enter the Binnenhof. The only difference with reality: in real life, the entire fence is not there yet, and people are still working hard to complete it.
"Heijmans is responsible for the architectural and technical installation renovation of the Upper House (or Senate) and the Council of State," says Thomas, who works for Heijmans as a BIM consultant. "This is a large-scale project, in which we and other builders are involved. We are working on our own part of the complex, but there are also overlaps - between the Council of State and the Lower House, for example. And the emergency route runs through various parts of the complex. So we have to make mutual agreements and check whether everything fits together properly. This kind of BIM helps us do that.”
Millions of points
The 3D model simulates the renovation of all the parts of the complex. Heijmans regularly works with such models if the size, budget and possible risks of a building project make this necessary. From 2023, the use of models will even become standard. But digitally mapping centuries-old monumental complexes, spread over some 89,000 square metres, is not something you do every day.
"An external company scanned the entire Binnenhof and its immediate surroundings using pointcloud scanning," Thomas says. "You put a tripod with a rotating operator in a spot. In each rotation, measuring points are shot into space and these are then digitally linked back to the operator. If the operator does this tens of millions of times, you get a pointcloud that represents what a space looks like." Heijmans will use the 3D design of the existing situation made using this method as a basis to work out the design of its own sections of the complex.
The model gives an overview of all elements - including all the walls, doors, light points and air vents - and quantities, materials and finishes. This is useful when materials have to be purchased or maintenance is required. The builders and the client, the Dutch government's Central Real Estate Agency (Rijksvastgoedbedrijf), all work in the same digital document. This means everyone has access to the same information, which they can all find in one place. This minimises errors and consequently failure costs.
The model also shows how the building site will be laid out, in each phase of the renovation, which is set to last for more than five years. "That building site will be a factory, a production site in public space that is constantly changing," says process and environment manager Bauke van der Goot. He has to make sure that everyone involved can work together smoothly and that stakeholders, like the city council and local residents, are kept up to date.
"Pipes need to be moved, a basement is being built, we need to be able to get large beams into the building and the logistical flows and escape routes need to be properly marked. By digitalising the building site, we can check whether it all fits together and can be done safely. You can see exactly where the lorries and emergency services can drive, even in a few months' or in five years' time. This means we can coordinate the project together: is this a place where we can all work?"
A 3D model is an extra investment, but it definitely pays off, says Bauke. "You can work together more quickly and efficiently and immediately test choices against practice." An additional advantage: it requires fewer physical visits to The Hague.
The 3D model also helps to give those without architectural knowledge a clear idea of the planned work. "I always take the 3D pictures with me when I talk to people living in the neighbourhood and businesses in the area," says Bauke. "It's a useful tool for communications with people in the local environment."
In the future, VR could also help with this, Thomas adds. "For example, you could have the fire brigade walk through the building site virtually wearing VR glasses to check whether the fire prevention measures are adequate."
For newer complexes, such as the Lower House, existing architectural drawings could also be processed in the 3D model. But the buildings that Heijmans is working on are so historical that old drawings would be very little help. "With buildings that are eight centuries old, you really have to rely on the scan results," says Thomas. Even so, you can still come across surprises. A medieval staircase was recently discovered in the Binnenhof, near the main entrance to the Upper House "It was only just discovered, during the foundation survey."
Pointcloud scanning cannot predict such discoveries, says Bauke. "But in projects where the old and new worlds come together, we know we are going to come across such things. We have set aside time to investigate them." Any relevant finds made during the more detailed investigation, from historical surprises to possible asbestos in the walls, are also included in the 3D model, Thomas says. "This mean that at the end of the process, you have a reliable model that gives you a complete picture of how the buildings are put together."