Subway-Induced Vibrations in Cologne Cathedral

Abstract

The Cologne Cathedral, the largest Gothic church in northern Europe and a World Heritage Site since 1996, is located in the heart of Cologne, a city of one million inhabitants in western Germany. Some 150 m from the Cologne central train station and 350 m from the Rhine River, one of the busiest waterways in Europe, and right next to a busy street and a high‐use parking garage, it receives manifold ground motions of anthropogenic origin. However, when the constant daily stream of tourists, about six million annually, ceases in the evening hours after the church is closed to the public or during church services, the building becomes an oasis of silence despite its location right in the city center. Since 2006, the cathedral is equipped with five permanent strong‐motion stations which are part of a strong‐motion network covering the Lower Rhine Embayment (Hinzen and Fleischer, 2007). All stations use Epi sensor accelerometers and record continuously at 250 samples per second. Set up of stations and measurement examples from the cathedral have been given in detail by Hinzen et al. (2012). On 9 December 2012, a new subway line of the Kolner Verkehrsbetriebe (KVB) went into operation. It utilizes a tube that runs in proximity to the cathedral and, right from the start of its operation, vibrations and solid‐borne sound became sensible, mainly in the northeastern part of the large building (ground floor 7914 m2) and in the choir. In early January 2013 this fact became public and caused a media storm including reporting in the German evening news and newspaper articles in Russia and China before any countermeasures could be taken. This negative publicity was extreme. One reason was that during the construction of a new subway line in 2004 the 44 m tall tower of the St. Johann Baptist church, 1.38 km …