Cologne’s City archive building had not been underpinned or compensation grouted despite its proximity to the underground works being carried out for the Cologne North-South light railway, a Cologne transit authority Kölner Verkehrs-Betriebe (KVB) spokesman revealed today.
“No underpinning or compensation grouting was carried out for the archive building as there was no indication that this was necessary,” said a KVB spokesman.
Advance securing measures had been taken under other buildings. Foundations were secured by underpinning and a total of 48 buildings were supported by compensation grouting.
In addition, monitoring of the neighbouring underground excavation had not picked up any unusual movements prior to the collapse.
“The tunnelling was monitored by a barometric level measuring system at the surrounding buildings and extensometers every hundred or so metres in between the tunnels as they were being built,” said the spokesman. There was also a measuring device in the walls but the thing is to my knowledge, this didn’t show anything prior to the accident.”
The archive building collapsed on 3 March along with residential properties on either side. One person was killed and another is still missing.
Cologne police said the collapse was caused by the ground under the building slipping into a underground excavation.
“Earth under the archive building slid into the tunnel of the subway, causing the building to collapse,” said a city of Cologne spokesman.