Wehrhahnlinie Düsseldorf
Continuum and Cut
The Wehrhahn Line Düsseldorf is one of the largest and most sophisticated recent urban development projects, reaching its successful conclusion after 15 years of construction and planning. Highlight of this project is the design of the new metro tunnel and the six metro stations. Architecture and art strikingly come together, characterizing impressions of the spaces. The artists also contributed to the remarkable decisions as equal partners from the beginning of planning and have not permitted any advertising spaces in the new stations. The New York Times says: "Art and magic in a German Metro". The project was implemented by the office of netzwerkarchitekten from Darmstadt together with artist Heike Klussmann, who together in 2001 won the EU-wide architecture competition for all six stations against major international competition. Together they developed the overall concept of a metro tunnel as an "underground continuum," similar to a giant snake as it slips through the earth, widening at the respective stations before continuing on its path. The stations are connected via openings to the urban space, each maintaining its own identity while acting as a connection to the city above. During the second competition in 2002, artists Ralf Brög, Ursula Damm, Manuel Franke, Enne Haehnle and Thomas Stricker were selected. Together with the architects each developed a specific design for the access areas of a specific station. Additionally, Heike Klussmann undertook the design of the continuum and the Pempelforter Straße.
Wehrhahnlinie Düsseledorf – Continuum
6700 individual concrete diamonds - A new material development and production process
The production of the concrete diamonds rhombi for the continuum by Heike Klussmann and netzwerkarchitekten would not have been possible without research into material development and production processes. In close collaboration with the manufacturer Schwab-Stein in Baden-Württemberg new production processes were developed, making it possible to produce panels with extreme geometries that do not require additional structural bracing while achieving a high degree of precision and surface quality. The emphasis was above all especially even surface, acute angles and precise edges. Precast fair-faced concrete sections are generally produced using formwork. This means concrete is poured into prefabricated casings as a hollow form where the casing side is visible and the filled side is to the back of the finished piece. Because this method only makes sense when it is used for a large quantity of identical elements, a different approach was used for the realization of continuum.
All of the 6700 individual diamonds of continuum were cut from blank slabs and produced with a vacuum filter molding method. The mixture consisted of high-performance concrete, aggregates of Nordic white and quartz sand and, for the pigment, 130 grams of black iron oxide per 100 kg of raw mixture. It was only possible to produce the light color with complete consistency using the specially developed mixture: cement and aggregates with a precise amount of added pigment. Then, the basic mold was filled with the raw mixture, leveled and homogenized, so that the material was evenly spread throughout. The homogenized raw slab then went to the concrete slab press (a 65-ton press, the largest in the world) and was pressed or rather compressed with a force of 3,000 tons per minute; in the process, up to 50% of the water was removed. This was followed by a hydraulic hardening process in optimum climatic conditions over two days. The back of the highly compacted base slabs was then calibrated and milled on the surface so that flatness tolerances in accordance with DIN V 18500 were achieved. After another storage period to achieve the final hardness, the slabs were cut and reworked. At this point, the diamonds for the Continuum were positioned using a photo supported detection system to use as much of the plates as possible and then a 5-axis CNC saw cut the slabs into the individual diamonds. Finally, the edges were profiled and four anchor holes were drilled into the back of each diamond panel.
In order to form the edges a special scheme was designed to guarantee that inspection requirements would be met. Classification as “bottom” or “top” fold panels meant that entire area of the building shell remained accessible and each individual diamond panel could be removed. At the same time, joints required no sealants and the mounting remained invisible. The minimal waste that was created was 100% recycled and reused as aggregate. The surface of the panels was then finished by applying a water-repellant coating and anti-graffiti protection.
All of the 6700 individual diamonds of continuum were cut from blank slabs and produced with a vacuum filter molding method. The mixture consisted of high-performance concrete, aggregates of Nordic white and quartz sand and, for the pigment, 130 grams of black iron oxide per 100 kg of raw mixture. It was only possible to produce the light color with complete consistency using the specially developed mixture: cement and aggregates with a precise amount of added pigment. Then, the basic mold was filled with the raw mixture, leveled and homogenized, so that the material was evenly spread throughout. The homogenized raw slab then went to the concrete slab press (a 65-ton press, the largest in the world) and was pressed or rather compressed with a force of 3,000 tons per minute; in the process, up to 50% of the water was removed. This was followed by a hydraulic hardening process in optimum climatic conditions over two days. The back of the highly compacted base slabs was then calibrated and milled on the surface so that flatness tolerances in accordance with DIN V 18500 were achieved. After another storage period to achieve the final hardness, the slabs were cut and reworked. At this point, the diamonds for the Continuum were positioned using a photo supported detection system to use as much of the plates as possible and then a 5-axis CNC saw cut the slabs into the individual diamonds. Finally, the edges were profiled and four anchor holes were drilled into the back of each diamond panel.
In order to form the edges a special scheme was designed to guarantee that inspection requirements would be met. Classification as “bottom” or “top” fold panels meant that entire area of the building shell remained accessible and each individual diamond panel could be removed. At the same time, joints required no sealants and the mounting remained invisible. The minimal waste that was created was 100% recycled and reused as aggregate. The surface of the panels was then finished by applying a water-repellant coating and anti-graffiti protection.
Wehrhahnlinie Duesseldorf Continuum
A new material development and production process
For the production of the 6700 individual concrete rhombi a new production process was developed, , making it possible to produce panels with extreme geometries that do not require additional structural bracing while achieving a high degree of precision and surface quality. The emphasis was above all especially even surface, acute angles and precise edges.
Wehrhahnlinie Continuum and Cut
The new Düsseldof Subway Wehrhahnline – A Synthesis of the Arts
Publication to accompany the opening of the Wehrhahn-Linie Düsseldorf in February 2016 as well as the exhibition: “Continuum and Cut – The Dusseldorf Wehrhahn Line – A Synthesis of the Arts”, April 30 – June 9, 2016, in Aedes Architecture Forum, Berlin.
Texts by Gerrit Gohlke, Gregor Jansen, Gerhard Matzig, Regine Müller, netzwerkarchitekten, Sabine Maria Schmidt, Anja Schürmann, Ludwig Seyfarth, Andrea Sick, Heidi Stecker, Oliver Tepel, Rob Wilson
Gestaltung Mario Lombardo und Enver Hadzijaj
Texts by Gerrit Gohlke, Gregor Jansen, Gerhard Matzig, Regine Müller, netzwerkarchitekten, Sabine Maria Schmidt, Anja Schürmann, Ludwig Seyfarth, Andrea Sick, Heidi Stecker, Oliver Tepel, Rob Wilson
Gestaltung Mario Lombardo und Enver Hadzijaj
Interview
Wehrhahnlinie Düsseldorf
15 YEARS OF PLANNING AND CONSTRUCTION ON THE WEHRHAHN LINE
A conversation with Heike Klussmann, Jochen Schuh and Markus Schwieger by von Regine Müller, published in Wehrhahnlinie Düsseldorf, continuum & cut, Kerber, 2016.
Download interview PDF >>
A conversation with Heike Klussmann, Jochen Schuh and Markus Schwieger by von Regine Müller, published in Wehrhahnlinie Düsseldorf, continuum & cut, Kerber, 2016.
Download interview PDF >>