WRITTEN QUESTION E-2738/01

by Erik Meijer (GUE/NGL) to the Commission

(5 October 2001)

Subject: Extremely tall, vulnerable buildings and standards for their supporting structures and demolition

1. Can the Commission confirm that, in the towers of the World Trade Center in New York which was destroyed on 11 September 2001, stability was not provided in the customary manner by a core containing stairwells and lift shafts but that steel columns in the outside walls were designed to support concrete floors, and that such floors may become detached due to distortion caused by heat, damage to the outside walls or overloading and may consequently collapse on top of one another?

2. Is use of the above construction method confined to America, or have similar buildings been built or designed with a view to future construction in EU Member States?

3. In the light of the data at the Commission's disposal, would the stability of high buildings, and thus their ability to withstand collapse, be increased if two supporting structures were combined, so as to provide support both from the core and from the external walls?

4. If there are no rules designed to maximise the safety of supporting structures in such extremely high buildings, will the Commission seek the adoption of common minimum standards at European level?

5. Has sufficient thought been given to how such high buildings in surroundings with a high building density can be demolished when they come to the end of their lives and how, in the interests of safety, the number of storeys in existing buildings can be reduced if this is felt to be desirable without this work causing storeys to collapse, thereby endangering their surroundings?

6. If there are no minimum rules with a view to the safe demolition of such extremely high buildings, will the Commission seek the adoption of common minimum standards at European level to ensure that, at the construction stage, consideration is given to how buildings can be demolished safely?

Joint answerto Written Questions E-2737/01 and E-2738/01given by Mr Liikanen on behalf of the Commission

(27 November 2001)

After consultation with experts and related literature, the Commission can confirm that the two Twin Towers in New York had the same structural design including a substantial central core containing shafts for lifts, stairs, ventilation etc, serving as a stabilising element against horizontal impacts. Steel floor elements were supported by this nucleus and structural elements integrated in the façade. Both these support mechanisms are necessary for a safe and functional structure of such dimensions.

The design method used for the Twin Towers has been used several times in the United States, whilst European high rise building design principles are based more on concrete technology. The Commission does not know of any high rise buildings designed without stabilising measures.

Very few civil engineering works are designed to resist an impact like the one suffered by the World Trade Center (WTC) Towers on the 11 of September 2001. A thorough investigation will be necessary to fully understand the complex chain of events leading to the collapse of the two buildings. This could result in important data influencing future designs, calculation methods and regulations.

The time span from crash to collapse was 47 minutes for the South tower and 1 hour and 44 minutes for the North tower. It is therefore likely that the collapse was due to the heat from fire, weakening the strength of the steel, rather than the physical impact from the crash as such.

The Commission is aware of the fact that high-rise buildings have been erected in several cities in Member States in accordance with the relevant national and/or local building regulations covering safety and other essential requirements related to the works. The Commission does not have an inventory of these constructions or their characteristics, given the fact that it has no competence in this field.

The Community's competence concerning the regulatory aspects in construction is limited to the Internal Market aspects of construction products, while the building regulations, including safety levels, remain a national matter. In this framework, the limitation of the height of buildings, for safety or other reasons, remains a responsibility of the Member States. It is obviously understood that height is one of most important parameters to take into account when assessing the safety of a building, in particular the mechanical resistance and stability, and safety in case of fire.

Member States have also regulations for the demolition of buildings as part of their building codes. The Commission deals with this issue in the framework of both its competitiveness and environmental policies. A joint task group comprising representatives of the Commission, Member States and industry has addressed aspects of the demolition of construction within the framework of the Communication on the competitiveness of the construction industry(1). The final report gives a number of recommendations to designers, industry and public authorities. Further measures in this area might be called for.

Concerning the potential need for minimum European safety standards for buildings, the Commission would like to inform the Honourable Member that, together with European Committee for Standardization (CEN), it is working on a set of design and calculation methods, called Eurocodes. It is expected that the first Eurocode standards will become available end of 2001 while the remaining eight important standards should be finalised during 2002. However, the Member States still remain responsible for introducing national safety levels. The final aim is only to develop a European safety assessment methodology.

(1) COM(97) 539 final.