There have been disputes between the council and the architects for more than a year. City executive Wolfgang Fuchs has repeatedly accused them of submitting incorrect schedules and implementation documents and has threatened to sue for damages. In May, the Berlin firm issued a new schedule to coordinate the more than 50 companies involved.

However, the city, as client, is still far from satisfied. “Despite repeated written demands and personal discussions, there has not been sufficient improvement by the project planner in their on-site presence and the coordination services of the planners, specialist planners and companies involved in the construction,” writes the administration in a confidential draft resolution. “Planned deliveries are also still inadequate.”

Drees & Sommer is now to close this gap using additional staff. The firm is already involved in the Beethovenhalle renovation as project manager and knows the construction site in detail. The city wants to charge the additional costs to the Berlin architects. Nieto Sobejano Arquitectos is not allowed to comment on the allegations without the consent of the city. “We deeply regret the situation and ask for your understanding,” said the office on Friday.

The problem is that disruption to the construction process triggers a chain reaction among the trades involved. According to the city administration, the companies have already issued 164 notices of delay, which are generally associated with additional financial claims. These are also reflected in so-called supplements, which according to the documents have already reached a total amount of 12.6 million Euros. The city has enlisted a specialist company of experts to review the supplements.

The forecast cost of the renovation now lies at around 79 million Euros. An additional 1.4 million will be spent on new chairs and other equipment. At the start of 2017, the city had calculated a total of 61.5 million Euros. Costs have also risen steadily since then because well-established companies are demanding significantly more money than the City Building Management (SGB) had expected.

The city is not attributing the disrupted construction process solely to the architects. Problems with the subsoil, poor structural fabric and the statics of parts of the Beethovenhalle – which according to city executive Fuchs were not foreseeable – almost brought the renovation to a standstill in February this year. The press office could not answer at short notice the GA question on Friday as to whether and how these technical difficulties have been solved in the meantime.

The city expects the listed concert hall to be ready “in the first half of 2020” according to an answer to a major inquiry by the Bürger Bunds Bonn. Many events for the Beethoven anniversary year will therefore have to be moved - most of them into the opera house.

(Original text: Andreas Baumann. Translation: kc)