STUVA explores a sustainable future
Dec 2011
Armand van Wijck, TunnelTalk European Correspondent
- Stockholm's Citybanan and Cologne's metro renovation projects took centre stage at the popular biennial STUVA conference in Berlin, which this year focused on establishing communication as a way of building trust between project managers and local residents.
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Site of Cologne's devastating collapse
- Citybanan, the railway tunnel project in Stockholm, took the coveted prize at the opening of the STUVA 2011 event, which also highlighted the issues of underground construction for sustainable environmental and climate protection. The tunnel, scheduled for delivery in 2017, will divert Stockholm's commuter traffic from the busy main line and through the city. In the meantime, the conference heard, Cologne will have to wait longer for its North-South metro line to be fully restored and operational.
- "Citybanan is a clear signal that Stockholm is reaching out to a more sustainable urban traffic environment," said STUVA chairman Martin Ziegler as he awarded the STUVA prize to project leader Kiell-Ake Averstad.
- Stockholm needed to reach out, considering it still uses the same two railway tracks as it did in 1871. The difference is that nowadays 550 trains use the tracks on a daily basis, compared with the original 10. Since 80% of Swedish train journeys start or end in Stockholm, the entire system for long-distance passenger railways in Sweden suffers as a result of this bottle-neck. But until now there was no room to increase the frequency of all passenger train types, despite their heavy usage.
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6km tunnel alignment under Stockholm
- The 6km-long Citybanan tunnel is meant for commuter trains, which make up two-thirds of the total number of trains passing through Stockholm Central Station. Diverting the commuter trains into a tunnel of their own – underneath the existing ground-level tracks – increases the capacity for regional and long-distance trains passing through Central Station.
- As well as drilling and blasting their way through hard rock, contractors have the added complication of constructing an underwater bridge; where the tunnel passes the water, soft subsoil rules out the set-up of immersed tunnel parts on the sea floor. Instead they are installed on four support structures.
- Averstad said: "We've already blown away 60% of the hard rock, but we know there are more challenges ahead, such as the cross sections with other subways, and supply tunnels. This prize will give us more energy as we look to complete the project."
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Cologne metro renovation
At day one of the conference Jörn Schwarze, member of the managing board of the Kölner Verkehrs-Betriebe, gave an update about the recovery process of the Cologne North-South metro line. - He said: "The stations adjacent to the collapsed Waidmarkt station will not be operational till at least December 2012. The southern part of the metro line will be operational in 2014 and the Waidmarkt station not until 2018." Estimated costs lie between €620 million and €1 billion, an extra (financial) burden for the city.
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Conference heard a failing diaphragm wall was the likely cause of the Cologne collapse
- Initial salvage of the historic City Archive building - which collapsed due to a construction failure at the Waidmarkt track interchange - has finished. Surprisingly, only 5% of all books were totally destroyed, although a further 16% were severely damaged. "The salvaging pit had walls founded by piles, concrete beams and steel pipe protection to balance ground pressure. Grouting anchors and more piles were attached to the City Archive itself to avoid breaking to one side", said Schwarze.
- The most likely cause of the collapse was a failing diaphragm wall close to the city archive, he said. "In 2012 we excavate an investigation pit below ground water level. We envision a first inspection dive along the diaphragm wall in 2013", said Schwarze. "When we have located the damaged wall area we will pump out the ground water and freeze the ground below. This prevents further erosion. The City Archive and Waidmarkt station can then be renovated."
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Joint-fact-finding
The Kölner Verkehrs-Betriebe might take the keynote lecture of the STUVA conference to heart. Hans-Peter Meister, researcher at the German communication consultant firm IVOK, pointed out the importance of dialogue with concerned citizens: "When mutual trust needs to be restored, you need to create a space where citizens can meet authorities. You cannot simply ignore them." - He was referring to the heavily debated and controversial Frankfurt Airport extension; since the introduction of a 'mediation package' by IVOK in 1998 there have been no more demonstrations. But, warned Meister: "Conflict never disappears, although in this case we got rid of fear and obtained a fair collection of compromises."
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More than 1,400 delegates crowded in to attend STUVA 2011 in Berlin
- The mediation package is made up of different aspects. First of all it is about openness and inviting citizens into the development process, rather than seeing them as opponents. Also citizens should be treated as equals, they have to feel their concerns are taken seriously. "Furthermore we have to be transparent at all times. Things should not happen behind closed doors, and communication needs to be in an understandable language", said Meister.
- One of the problems in an information and communication-rich world, however, is the scope for misinformation and misinterpretation. Social media and rapid information spread on the internet is is not always helpful and can be misleading, or even false, at times. In view of this Meister proposes 'joint fact-finding' as an alternative communication strategy for sustaining a healthy dialogue, a method successfully used with regard to the Frankfurt Airport extension.
- Although not new, joint fact-finding has not quite yet been introduced in underground construction projects. It involves concerned citizens regularly meeting and debating with experts, contractors, initiators and politicians involved. Meister said: "All stakeholders will be in the same room. Citizens can make statements and receive consistent answers from the experts. Joint fact-finding prevents a highly emotional debate and in the end you get a widely accepted project."
Exhibition stands run by the industry's leading companies were a popular draw
- More than 1,400 delegates enjoyed the three-day STUVA conference, which was jam-packed with presentations about the latest developments in the European tunnelling industry.
- Köln - speculation and anger in aftermath - TunnelTalk, Mar 2009
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