Zwolle train station footbridge

unique footbridge

An innercity park, measuring 130 by 10 metres, elevated above the railway tracks, with a loadbearing timber bridge deck. That’s the sustainable and green footbridge at Zwolle train station in a nutshell. The innovative timber bridge was designed by a multidisciplinary team consisting of Karres en Brands(coordinating architect), ipv Delft (bridge design specialist), and German Ingenieurbüro Miebach (timber structures specialist). Two days of festivities will mark the bridge’s opening on September 5^th and 6^th .

The municipality of Zwolle, Dutch railway network owner ProRail , Pontico , and Attis were actively involved in the design process, and the wishes of residents and businesses were also taken into account. Dura Vermeer and Van Gelder were responsible for the actual build.

attractive elevated street design

The symmetrical S-shaped pedestrian bridge has the overall appearance of an appealing elevated street: trees, bushes, water, brick paving and plenty of seating make this footbridge a pleasant place to be. The bridge deck layout was specifically designed as a series of different environments, in which the line of view changes as one walks across. This way, crossing the railway tracks becomes an adventure, offering something to everyone’s liking. There is a main path, a fast direct connection, and narrower side paths that lead to sheltered areas and viewpoints. The main path has a slight zigzag shape, which ensures that the sightlines change constantly. Wide stairs with resting platforms and bicycle gutters and three spacious elevators make the bridge accessible to everyone. Bicycles are allowed, cycling isn’t.

maximum sustainability

Both client and design team were aiming for maximum sustainability. Therefore, a bridge structure in European soft timber was the design of choice. The bridge is comprised of four parallel 1,34 metre-high laminated timber beams with identical 34-metre spans, supported by steel portals. All timber is shielded from sunlight and water and designed to last around a hundred years.

European softwood structure

A timber bridge this size alone is quite rare, but the Zwolle train station footbridge not only has a loadbearing timber structure, but a timber deck as well. Given the amount of planting and water features on the bridge, this cross-laminated timber deck is especially unique. To ensure the deck is water tight, the layers of the bridge deck have been carefully thought out and designed to guarantee the watertightness of the top layers. On top of the CLT bridge deck is a double-thickness EPDM layer, topped by a sophisticated system for water collection and infiltration, both underneath the trees and shrubbery and underneath the paving.

Key in choosing a timber deck, was sustainability. When looking at various options and comparing aspects such as costs, maintenance and building process, a timber deck proved the most environmentally friendly choice. This inspired the design team to take a closer look at the material of choice for the elevator shafts, which resulted in a timber structure with high-end glass paneling. Again, a ground-breaking design decision. An additional advantage of choosing timber, is that the entire bridge structure can be dismantled.

structural design

The bridge consists of four parallel glulam beams, which are connected transversely with steel connectors. Because of their shape, the beams don’t appear to be the 1.34 m height that they are. The beams are supported by five portal-shaped steel supports. The design of the supports refers to old station roofs and overhead line portals, industrial and without fuss.

part of the city’s urban fabric

Within the urban fabric of Zwolle, the footbridge forms an important and high-quality new connection between the historic city center and the developments in the Spoorzone and Hanzekwartier, where a whole new and vibrant part of Zwolle will emerge in the coming years. Combined with the city’s green ambitions, the ‘park bridge’ is a logical choice.

The bridge has been explicitly designed as a public space. The routing is tailored to sightlines towards the Peperbus and the station building, among other things, and to creating a diversity of both recreational and purely functional areas. The planting design ensures that the bridge looks attractive and green in every season. Of course the location of the supports also influenced the design: the heaviest planting is located directly above the supports, because that is where the bridge can bear the most weight.

Not only does the public space continue on the bridge, but the staircases on either side have also been explicitly designed to create added value for users and the city. The stairs on the south side, for example, form an attractively designed grandstand with plenty of plants and slow running water, overlooking a new green area. At the bus station, the footbridge functions as a waiting area.

continuous architectural line

The connecting function of the footbridge is also clearly visible in the architectural design: the wooden underside of the entire structure forms a continuous line from one end to the other. The design of the steel bridge edge and the railing tie in well with this, both being subordinate to the wooden ‘main line’.

The bridge’s edge element consists of a steel edge beam combined with a recessed timber panel underneath and has two important functions. The overhang protects the outer bridge beams from direct rain and excessive sunlight. In addition, the height of the element as a whole covers the layers that make up the roof garden structure. Choosing a timber panel as part of the edge element ensures that the timber deck construction remains clearly visible as the bridge’s main architectural feature.