We regarded the invitation to design bridges and/or viaducts over the A7 motorway in Sneek, in competition with the major bridge-builders of the Netherlands, as an enormous challenge. Right from the outset we initiated an adventurous search for a design specifically appropriate for Sneek. Certainly in the preliminary stages, we did not allow ourselves to be distracted by the restrictions of technology or the brief. We resisted all-too-obvious solutions, we were searching for something unique. The pieces of the puzzle ultimately fell into place and the right people occupied the right places - a precondition of success!
In the search for a good design team for this project, an alliance was sealed between Achterbosch Architectuur from Leeuwarden and Onix from Groningen. It has been a productive co-operation, resulting in the current design for the bridges!

Connecting the banks

A simple plank across a ditch is an elementary link, or bridge in this case, between A and B. The function has been reduced to the basics. This awareness came at an important moment in our debate. We realized that this original form ought to be the basis for the bridge. In addition, we Realisation that the assignment meant creating connecting bridges at urban and provincial levels of the A7 motorway, at 'Molekrite', 'Akkerwinde', and the Lemmerweg connection (the fly-over roundabout/ junction). So we devoted our attention to the Molekrite and Akkerwinde connections.
The research was oriented to connecting the sides in a clever way. How does one generate or design a construction that has something to do with the location, the situation, the moment in time, etc? There then followed a research process in which many scale models were constructed in an attempt to find out whether or not it was truly possible to come up with an 'intelligent' construction. It was an adventurous period that led to much discussion on materials, the identity of the location on the A7, the relation to the Place, Frisian boat-building, and Sneek's general association with water. The discussion of whether the bridge or viaduct could be a building also played a role. Should the bridge be a moment for standing still, a point of tranquillity as is the case with lift bridges? Is the connection through the bridge or over the bridge?

Second stage of the research.

Many deliberations ultimately led to the second stage of the research. The preference for wood, expressed by both Onix and AA, led us to study the possible application of this material. Wooden bridges, large spans, and Frisian boat-building began to play an increasingly prominent role in the assignment facing us.
Historical research indicated that, in bygone days, many bridges were built of wood. We still encounter these so-called 'covered' bridges at many places in the world, and they are still used for traffic to this very day.

The bridge

The deliberations on the research, thoughts on the origins of bridges, our preference for wood, and the identity of the location all finally merged into a design for a wooden bridge. A study of shape, dimensions, and durability in particular led to the basic form of the bridge, which respects tradition but is also innovative - two identical trusses, which support the span from bank A to bank B with a road surface for pedestrians, cyclists and motorists. The rafters consist of tensile and compression struts and are sound in their configuration. In construction terms, the design refers to the tradition of 'covered bridges' but it accepts the consequences of modern times. In this stage, the wood constructor Emil Luning was allocated an important role in the design process and we challenged him to go to the limit. Craftsmanship and nerve were needed at this stage! The straight rafters that were impossibly large had to be adapted to the brief (traffic over the bridge). They eventually complied with the terms of the brief and a basic form of the bridge was generated. The design was born.
To us and to Emil Luning, it is an enormous challenge that the bridge will now be built from large double-curved laminated rafters that have been made more durable by an innovative process. It is unique and has never previously been implemented. The adventurous research process has now reached its climax with the generation of a scale model, where ideas and theories on paper are translated into a solid object. It is a magic moment. It is convincing, we can start to realize the bridge!

Hans Achterbosch / Alex van de Beld
Achterbosch  Architectuur / Onix
April 2005