The Arnhem Centraal Transfer Hall’s fluid shape was inspired by the region’s rolling topography and informed by expectations of how people will need to move through the building. UNStudio
Following years of delays, the last component of a new multimodal transportation terminal, in Arnhem, the Netherlands, is now under construction.
April 8, 2014—When was it was conceived in the late 1990s, the design of the new multimodal transportation terminal, in Arnhem, the Netherlands, was cutting-edge, its curved lines and flowing interior spaces developed by using parametric design processes. But finding a contractor to construct the serpentine structure was difficult, and as a result, the project was delayed. Now, construction of the terminal is well under way, and although its free-form design is not quite as trendsetting as it was at the time of its conception, the new terminal will still be an impressive addition to the Arnhem cityscape.
Arnhem Centraal Transfer Hall, as the new terminal is known, is part of a larger project to transform the existing Arnhem railway station into a public transportation hub known as Arnhem Centraal. The municipality of Arnhem; ProRail, the organization responsible for the Netherlands’s rail network; and NS, the principal passenger railway operator in the Netherlands, are leading the project. IN 1996 those entities retained the Amsterdam-based architecture firm UNStudio to develop a master plan for a new transportation hub that would replace the existing railway station and accommodate future high-speed rail lines as well as other modes of transportation—including buses and bicycles. UNStudio then designed the individual structures outlined in the master plan. The Amsterdam office of Arup, an international engineering firm, assisted with the master plan and is the structural engineer for several of the individual components of the project, including the transfer hall.
The 6,000 m2 transfer hall is the final component of the new transportation hub to be constructed. It will be located at the center of the development, which also includes a 7,500 m2 bus terminal and two office towers totaling 22,000 m2. The hall will have two below-grade levels for bicycle storage and vehicular parking and multiple undefined above-grade levels that will include a spacious entrance lobby, retail shops, offices, service areas for ticketing and related operations, and corridors that will link the train platforms, local and regional bus terminals, taxi stands, bike storage, and parking. “We tried to make one totally integral building that would house all of those functions so that each part would be seamlessly connected to the other,” says Joop Paul, a Europe region board director for Arup.
The transfer hall is the final component of the new transportation
hub, which will include a bus terminal and office towers, to be
constructed in Arnhem, the Netherlands. UNStudio
The hall’s architectural design was inspired by the region’s rolling hills—but was also informed by the expectations of how people will need to move through the building. Although the building’s flowing shape appears random, it was actually carefully designed using computers—an innovation at the time—to ensure that people could walk from one mode of transportation to another as efficiently as possible, Paul says. To that end, the hall will have a landscapelike quality: sloped floors will create a natural path through the building and a clear-span, double-height entrance lobby will afford unobstructed views to each transportation system. “There are no visual obstacles when you sit in the middle of the transfer hall [lobby]—you can see the taxi stand, you can see the entrance to the parking, you can see the entrance to the bicycle park, you can see the two bus stations, you can see the train stations,” says Ben van Berkel, a cofounder and principal architect of UNStudio. “That was one of the most important strategies we introduced in the project. The architecture provides the wayfinding instead of signs.”
To accentuate the hall’s undulating form, designers originally planned to frame the building almost entirely in exposed concrete. But when the project was put out to tender in 2009, all of the bids were over budget because the contractors were wary about guaranteeing the quality of the concrete work. “They thought it would be very difficult to get a concrete surface with uniform color, and they worried that it would have visible cracks,” Paul explains. “If any cracks were too big, they would have to fix them, which means they would have to do it all over again. That would be a very big risk.” The project was idle for several years as a result, but when it was put out for tender again in 2012, contractors were invited to propose alternative construction methods. The lowest bidders proposed building the hall of steel, and the proposal was accepted. The project is now advancing with a mostly steel monocoque structure. “They thought steel would be much easier to control because it would be lighter and more simple,” Paul says. “They also thought that they could build it more quickly and better guarantee the shape.”
The transfer hall’s entry lobby will have large clear spans, affording
unobstructed views to each of the transportation systems.
One area of the building in which the steel monocoque structure will enable the design to be more easily realized is the entrance lobby. The lobby’s clear spans are supported almost entirely by a single free-form articulated column—which the designers refer to as a “twist”—at the center of the space. By framing the roof at that location in steel rather than concrete, the forces on that column will be significantly reduced. “The twist in the middle captures all of the forces coming from the roof down into the central [lobby],” Van Berkel says. “It is almost like the steel element you hold in your hand when you carry an umbrella. It’s carrying the whole umbrella—the total aspect of the project.” The transfer hall will also have several cantilevers measuring up to 10 m long at the front of the building, projecting the office space in the hall’s top level out over its lower-level glass facade. In accordance with the original design, those cantilevers will be achieved using steel trusses.
Construction of the hall began in 2012, and although the designers are reluctant to put a steadfast time frame on the project because of the earlier delays, they do expect the hall to be completed sometime in 2015. While the building may not be as innovative as it would have been when designers began working on it nearly 20 years ago, Paul says it will still be an architecturally significant structure. “For me, the perfect blending of architecture and engineering has made this a project very close to my heart—the team is very proud of it.”