Aesthetic relief on bridge abutments
The abutments on a green bridge in Zwaluwenberg, the Netherlands, were created with the help of the new textured formliner series NOEliner from NOE.
A green bridge was built for North Holland Province in the countryside between Utrecht and Hilversum as an ecological improvement to the Utrechtse Heuvelrug national park near Utrecht. The project was designed by landscape architect Clim Sorée from Bosch Slabbers Architekten, an architectural practice in Den Haag, the Netherlands. The abutments on this bridge are notable in particular for the textured concrete finish on their walls. To create these textured surfaces while achieving the required concrete cover to the reinforcement, the designers opted for a texture from the new NOEliner textured formliner series from NOE-Schaltechnik, Süssen, Germany.
A green bridge is an engineering structure that provides a means for wild animals to cross busy roads and railways safely. To cater for the requirements of people and animals on this site, the designers had to take several different aspects into account. For example, animals must feel safe using the crossing. The first step was to spatially separate the animals from the people. The animals had also to be sheltered from artificial light and not subjected to alarming noises. To provide this separation and shelter, the wildlife path was densely planted at the edges, which had the knock-on effect of requiring a very wide bridge. In addition, the green bridge does not pass over the road at right angles. The bridge is highly skewed and runs at a very acute angle to the road. The reason for this: the alignment obstructs the view of other roads in the area from the green bridge, which makes the animals feel more secure.
Many motorists, pedestrians, cyclists and riders travel on the road under the bridge. Hence the designers sloped the abutment walls back from the road to widen the opening under the bridge, especially at the top. The walls are decorated with a relief, a stylised image of oak leaves and acorns. The simple, clear line pattern enhances the appeal of this motif. The lines vary in thickness and create the impression that they have been drawn with a calligraphy pen. The abutments display a readily recognisable and trusted motif, which gives the human users of the tunnel-like structure a feeling of safety and familiarity.
NEW: NOEliner textured formliners
The following applies generally to a relief: the deeper it is, the greater its shadow effect and therefore its sculptural appearance. However, in the case of the precast concrete panels for the green bridge abutments, the designers had to achieve adequate concrete cover to the reinforcement and therefore the allowable depth of the relief was limited. The solution: NOEliner. These formliners are only 2 mm (!) thick. They are made from hardwearing PVC and adhere very effectively to flat surfaces. To use these ultra-thin textured formliners, you simply stick them onto a formwork panel or supporting board. Then the concrete can be poured. As soon as the concrete has cured sufficiently, the forms can be stripped to reveal the relief on the precast concrete unit.
The designers chose the NOEliner texture Sand for the green bridge. This is only about 2 mm thick and is excellent for achieving maximum texture contrast with minimum depth. All the preparatory work was done in Arkel by NOE-Bekistingtechniek b.v., the Dutch subsidiary of NOE-Schaltechnik, Süssen. The NOE team attached a self-adhesive film on the back of the NOEliner and then precisely cut the required motifs to shape with a CNC-controlled cutter-plotter. The vector data required to do this were supplied by the architect. A total of 29 different motifs were created in this way. They were positioned like stickers on the supporting board with the help of the self-adhesive film. The boards were then placed into the forms and the concrete poured. NOEliner textured formliners can be used up to 20 times.
The national park now has a green bridge that aesthetically and from a practical point of view meets the high standards demanded and benefits people and animals alike.