C21 Transport synergies: Wood Town Eberwalde’s funky timber cycle hub
Nigh on exactly a half-hour commute northeast from Berlin to the Brandenburg town of Eberswalde, the thirty-minute train journey shuttling between the capital and dormitory town defines a difference in worlds. The glitz and bright lights of the cosmopolitan, connected Berlin fade away by the kilometre as the landscape becomes rural and increasingly forested.
Yet Eberswalde is not only an urban centre itself, but a major university town, and home to Northern Germany’s – and in effect Berlin’s – main forestry research university campus, Eberswalde University for Sustainable Development (HNEE). Dating back from 1830, HNEE is one of Germany’s older forest educational establishments. Comprising four forest-related faculties, research is focused on three core themes: sustainable rural development, sustainable production and use of natural products, and sustainable management of resources. Wood culture also informs much of the research agendas of each faculty.
Not only was Eberswalde Germany’s major northern forestry research epicentre, but up until quite recently the Eberswalde had been a timber town, and the region had contained a significant regional wood sector. So all-encompassing were the woods surrounding the ex-DDR town of forty-thousand, which was colloquially known locally as Waldstadt (Wood Town).
Yet, up until a few years ago any visitor new to Eberswalde would have been hard-pushed to have any clue about either this history or the major forestry research faculty on its doorstep. Handsome in parts, including along its main high street, post-re-unification industrial decline and decay marks many districts beyond the immediate centre.
In the mid-2010s the town’s mayor, Anne Fellner began talking up a major overhaul and upgrade around the rail station with other local politicians. What was needed was an appealing infrastructural something, symbolically meeting and greeting first-time arrivees to the ex-DDR university town of forty-thousand. Though modest and quiet, Eberswalde saw a regular flow of international visitors, and ones who’d appreciate a green gesture, researchers and academics heading to what in effect is Berlin’s main forestry research university campus. Close to the capital, Eberswalde was also a dormitory town with the daily ebb and flow of commuters shuttling between home and station. Many of these big city workers used bicycles for their weekday journeys first and last miles.
In 2018/2019 the municipality entered a city planning competition to redesign and remodel the area around Eberswalde’s railway station. Other funding, including grants for cycle infrastructure from Brandenburg state, were coming online along with EU funding were applied for. In initial discussions, Fellner said she wanted ‘something special’ made from wood – a symbol of the future as well as the past, and the first thing people would see, a landmark for those arriving in the town signalling sustainability in materials and transport mode. A proposal emerged for a cycle hub built and using local, untreated, chemical-free wood.
Among the contestants were Leitplan, a multi-disciplinary studio, urban designers and city planners. The studio was in a strong position having already completed a cycle hub in 2017 in Oranienburg, a similar dormitory town, and this time directly north of Berlin, and subsequently were awarded the project. Two years later, in 2019, the studio submitted a master plan for the rail station which included the timber cycle hub.
But their Oranienburg Parkhäuser was an all-steel and concrete affair, the studio possessing scant knowledge in timber as material for design and architecture. Not just timber either, but other challenges. Fellner envisaged a cycle hub made from local, untreated, chemical-free wood. “It was the council’s wish and we,” says Leitplan’s project architect, Nora Zimmermann, “tried to find the best solution.” It was to prove difficult though.
For the timberwork, Leitplan turned to an engineering consultancy with a long history of working with timber: ifb frohloff staffa kühl ecker. When I talked with Zimmermann she described the original design as a very open pavilion, before noting that the consultancy’s engineer for Eberswalde, ifb partner Michael Staffa, “understood the idea. He’s a very creative engineer.” He also, she acknowledges, had the idea to make the construction of the design.
“It was a design that he had always wanted to do. Architectsand engineers worked together, figuring out the design” she says. When I called him up a few weeks after visiting in spring 2023, Staffa added to this description: the architects didn’t really design the structure, rather, he did.
The result is a compelling and complex piece of timber engineering. Opened in 2021, the Eberswalde bicycle garage sitting on the far western side of the station approach and flanked by a large-tarmacked open space for buses and drop off/pick up areas, is a dramatic presence. The two-storey timber structure consists of interlocking rhomboid columns, the lozenge diamond forms running its length and breadth creating an uncanny optical effect. The diamond columns, consists of the 1.7m grid struts and crossing at the ground floor ceiling and upper roof, are broken by two A frame type entrances along the front of the hub, and a single one at its back, providing access to the ramp’s entrance up to the second floor. The lozenge grid struts also feature internally on the ramp’s sides. Above, dropped over the top of the upper floor is a thick wood deck, three layers of thin cross beams pushing out to provide a deep and protective overhang, while photovoltaics add a further layer atop the deck’sroof.
A seemingly simple yet effective structure, the cycle hub appears well resolved and geometrically satisfying. As Staffa recounts, the engineering needed to make the structure work was straightforward, making its omplexity clearer.
The three-layered deck system comprises two sets of three beams running crosswise, at 900 to each other. As the design needed the deck to cantilever out equally over the building’s façade edges on each of its four faces to protect against rain, the initial challenge focused on achieving this. Normally, an efficient solution would have left the overhangs unequal, but would have made the design look clumsy and unresolved.
Staffa arrived at a solution, what he refers to as a Balkenstapelrost, which I translate as a ‘stacked beam-grid’, or grid deck. At its simplest the stacked grid comprises laying out a parallel series of long timbers, stacked alternately to build up strength, not unlike a children’s game. But the engineering is complicated, and the Eberswalde beam-grid deck took time. One reason for the in-depth gestation, Staffa says over the phone, was the design engineering, particularly the statics problems, what he refers to as the ‘Greek edge’ problem. Ensuring all four edges were the same and that the deck cantilevered out equally on all four faces was particularly demanding. “I had to find a construction where the 3.26m cantilever was equal on all sides” he notes. The edges are the reason why it is made of three layers. For instance, “It would have been easier if it had begun at the middle of the roof, but it begins at the edge.”
The stacked-beam grid was the solution, although this immediately created a new challenge. Conventionally, the cross beams would require the empty spaces between them o be filled. “I’d have had to fill the empty space with other beams,” as part of the static engineering parameters to ensure the structure stayed standing and fixing these small beams to each of their immediate neighbouring cross beams.
Staffa decided to leave as much empty space between the grid of beams as possible. “That was my new idea; to fill in the space only where it was statically needed following the shear force curve.” He also broke the deck into six partial grids, which helped with the structural engineering calculations.
Next Staffa worked on his three-layer stack by hand, “filling in the beams where needed for the vertical load. “We discussed whether to use a Grasshopper programme, Caramba, but I decided to do it by hand. It is quicker and I trust it more. I’ve been doing timber engineering for thirty years, after all.” This piece in the engineering process resolved the shear forces in the deck, and not normal made the construction much lighter.
But making the deck’s four edge faces equal meant considerably more timber being specified. Greater use of timber resolved its edge aesthetic but meant, in Staffa’s view, a less elegant solution as far as minimising the amount of material used. He wasn’t sure that the extra cost would get through the value engineering, but when it came to the decision the increased specified timber was waved through without any comment.
It’s not a completely unknown dilemma, he notes. Staffa has been working on another showcase, this time a performance hall in Magdeburg, Saxony Anholt with the same issue of needing additional timber. “They wanted something special and it’s a crazy construction” he says, while concentrating the project team’s minds and attention.
“It’s very loud,” he says of Eberswalde. “I love it, though I recognise a construction which minimised materials would have been less wasteful and an interesting approach. There’s times I have a bad conscience about this.”
Still, he seems pleased with the result, not least the carpentry company’s delivery and realisation. “They had a brilliant work plan; you never know how it’s going to go after you hand over your stage in the programme. I was onsite and the carpenters said, ‘We love it, such good planning, it’s incredible!’”
The hub’s two floors reach 7.5 meters in height, while 39m long and 17m wide. Zimmerei Thielke, a carpentry company from Luckau in Lower Lusatia, Brandenburg, about eighty minutes south of Berlin, won the carpentry contract, which Staffa praises so highly. Larch was specified throughout: 60m³ of larch was used on the façade, another 31m³ for the two ceilings, and 133m³ for the roof deck. The unusual roof deck is made of eight pieces, with the beams raised while still working on the first floor. To connect the glulam columns to edge joists the carpenters drove dowel pins and rods and recessed dowels together friction locking the wood-to-wood connection. The deck rests on a wooden ceiling made from 39mm veneer plywood LVL-X panels, over which bitumen and a nailed roofing membrane were placed, followed by a welded polymer bitumen membrane commonly used on concrete bridges and other exposed surfaces. Almost fifty-thousand screws were also used on the building, primarily on the roof construction.
When the timber specifications were being finalised things got complicated. “There are so very few options: German oak, or Siberian larch,” says architect Zimmermann looking back. Finally, Zimmermann recalls, Thielke decided upon pre-weathered untreated Siberian larch glulam beams, turning to one of the few larch glulam specialist manufacturers with the gluing capacity needed, another regional firm, Holzwerke Bullinger. At about double the price of the usual spruce glulam Bullinger generally supplies, when I ask about the larch, Zimmermann looks a mite sheepish and notes it was likely bought – given its cheapness – from Russia, the summer before the Ukraine invasion. This is despite Bullinger highlighting local provenance on their website.
Designed through Covid in 2020, and built mainly in 2021, Thielke prepared the glulam columns and beams through the first winter, the timetable needing completion by the end of the year. But the schedule was thrown into disarray by the internal flooring asphalt failing, and consequent remedial works pushing the schedule back. The carpenters were, according to Zimmermann, “very professional”.
By winter 2021 the ground floor was opened, while at the same time, the first floor was still being worked on. Finished in 2022, the hub was opened in the summer by Brandenburg’s Minister for Transport. Lined with rows of bike racks, in all providing six-hundred-and-four bike places, Eberswalde cycling residents have struck lucky with the hub. There are personal lock-up bike boxes, and other safety features, all offered free to Eberswalde residents, plus power connections for e-bikes, cargo bikes, and trailers needing electricity, the energy coming directly from the PV array on the roof. While visiting I am told it is considered their – the town’s people – cycle station.
Since its opening the Cycle Hub has been well received, it is safer to leave one’s bike, and locked up, less liable for being stolen. It has picked up an award or two, including a special award in the regional 2023 Brandenburgischer Baukulturpreis.
For Staffa Eberswalde provided the context to test and take steps further a research agenda the engineer has been immersed in for years. Likewise, the ifb engineers have worked with timber for over forty years, including several CLT housing projects across Berlin and others: their website list of timber projects on their website is indeed impressively long. Staffa is excited at the recent growth of timber. “It’s incredible what’s happened in the last fifteen years. It’s a new subject. We didn’t even think about it. “
Asked about influences Staffa points to the work of Julius Natterer the Bavarian engineer who headed up EPFL’s I-Bois for many years, noting he “was very, very inspired by his lectures and buildings. But Eberswalde didn’t need as much timber as Natterer would have needed.” Further – Julius Natterer interview in FDR6.
“The most important thing with Natterer was that you can think of nearly every construction in timber. With his grid constructions you know, what he did with me.”
You can see the influence of both the late Natterer, though also his contemporary, Frei Otto, who did so much pioneering research on gridshell structures, in the engineering of Eberswalde’s triple-layered grid that its deck sits on. It’s an engineering continuing in the spirit of those two great German engineers, though Staffa also cites Munich architect Florian Nagler’s Kirchenzentrum Riem which applies a boxed layered grid. Indeed, Eberswalde is hardly the only ‘stack beam grid’ structure that Staffa and ifb have been working on. Working with students at Hamburg’s Hafen City University, they examined what were clearly research predecessors to Eberswalde culminating in EXIL (Experimentelles Interdisziplinäres Labor) in 2007. The deck, described as a Holzstapelrost, consist of four interconnecting beam layers, running crossways to form a knotty lattice roof sitting above a cuboid pavilion, encompassed with lightweight glazed plastic sheeting. EXIL provided the live R&D and testing of the system that Staffa developed for Eberswalde.
Next up in this iterative series is the Festhalle Magdeburg, Staffa’s ‘crazy concert hall’ for the city’s Rudolf Steiner School, the roof looking something like an armadillo’s plates, this time on a more complex non-orthogonal design. At present, the concert hall is due to open in 2026.
If the Eberswalde bicycle hub finally provided the opportunity to test Staffa’s stack beam deck engineering research on a live project, the building provides a striking synergy of cycle infrastructure and timber design, an illustration of how two modes of drawing down our carbon footprint, in travel and construction, can be achieved. Staffa is chasing an engineering end, and the green transport showcase is almost incidental. Leitplan, who, when I visited in 2023, was looking at a new cycle hub in Berlin city itself, are focused on rethinking infrastructure. “We’re trying to get it on the city agenda, it’s happening slowly,” said Zimmermann. “They’re thinking about a network or set of hubs. It will make sense to make a construction system if this happens.” Timber, and hopefully more locally sourced timber, will be part of the system, though whether there’ll be such fancy and experimental roof decks to the speculative system was left unspoken. Likely not, given the extra cost. But with the Eberswalde Bicycle Hub two leading edges of radical green thinking: bicycles and natural materials – in its timber guise – are meshed into one. In doing so, they depict alluring pathways into the future possible.
