An aesthetic traffic engineering plan
Bridges are complex functional machines with many components that as a whole ensure that traffic on water and land can move safely. In a place as special as the Muidertrekvaart with its beautiful trees and long sightlines, a carefully designed composition is essential. The most difficult task is bringing both types of bridges (traffic and bicycle bridges) that are very different in size and height together. We found the solution in an expressive construction that the Municipality of Gooise Meren has chosen as winner of the tender. Parapet and deck merge together to form a fine perforated surface. Cars, cyclists and pedestrians look right through it, while technical details such as opening and removability, direction of rotation and construction are subtly incorporated in the design. With both bridge types, the required supports are as far away as possible from the center of the canal. This creates the lightest possible crossing over the water. The necessary technical aids such as barrier boxes and fenders are kept separate from the bridge structure and are as simple and minimal as possible which results in a coherent, calm image as a whole.
Modest integration in the monumental Trekvaart
The Muider Trekvaart is a monument, the forerunner of the A1 motorway. In the golden age it was the fastest and most comfortable interurban connection. Now the Trekvaart is quiet and above all a beautiful space with a wet floor and a green roof. The double row of trees on both sides of the towpaths offers shelter to the passers-by and a beautiful view over the water and adjoining open meadows. In our view, the long lines of the Trekvaart should therefore be interrupted as little as possible. We achieve this by making the bridges as transparent as possible, with extremely slim decks and “transparent” railings. All three bridges have a pronounced horizontal character even when opened. Together they form a modest addition that does not compete with the beautiful long lines of water under the bridges and the crowns of the trees above.
Inspiration from the military / utilitarian past
Muiden has been a place with a military, utilitarian image for centuries. There are many monuments such as The Muiderslot, the forts of the defence line of Amsterdam, the Groote Zeesluis and its swing bridge and of course the site of the former Kruitfabriek. The common denominator of all these historic buildings and constructions is a utilitarian character. No fuss and frills, but efficient and austere architecture where functionality is paramount. The new district the Krijgsman is spread on this firm context. We were also inspired by this simplicity and looked for a twenty-first century translation of the archetype of the military utilitarian bridge: the famous Bailey Bridge from the Second World War.
Durable and rather maintenance-free operation
We chose an electromechanical operation for rotation of the bicycle bridges. This method has been successfully used many times with movable small-scale bridges. Electromechanical spindles are strong, use very little energy (a capacity of 1 KW is sufficient) and are almost maintenance free. The free placement under the deck makes the spindle directly accessible for inspection. The spindle box is attached to the rotating bridge deck, the rod is attached to an arm fixed on a fixed column. In the normal situation (when the bridge is in use) the spindle is relaxed. When the spindle is activated, it pushes itself on the arm and pushes the bridge deck 90 degrees. The bridge deck rotates around an axis that pivots in the fixed column. This construction is robust and has only one rotating part: the heavy axis in the middle. The expected lifetime of this main mechanism is 100 years. The lifetime of the spindle is expected to last several decades.
Aesthetically conscious detailing
We translate the power and simplicity of the Bailey bridge’s composite trusses into our time. The load-bearing railing remains, but is now laser-cut from a steel sheet, so that it can be made quickly and accurately, with a high quality finishing. The perforation patterns are designed and cut out in a computer-controlled method. Where structurally needed, reinforcement partitions are welded on the inner side of the parapet. We expect a continuous truss to be needed at the road bridge and only a local stiffening in the bicycle bridges’ structure. Both bridge types have as light as possible decks: composite elements that span from one side to the other on slim steel profiles. In this manner, we achieve extremely thin decks thus, optimum transparency. The lighting is integrated in the structure. Aesthetic integration goes hand in hand with optimal socially safe lighting and vandal resistance.
The theme of the oblique ending and the military color of the parapet is also reflected in the barrier box and the control panel. We have paid special attention to full integration of movement work in architecture. Movement of the swing bridges and dilatation of the removable part of the road bridge have been refined into the details. They have been consciously made as subtle as possible. An image that is as calm as possible is our priority.