Project planning

Case study: transfer of the A1

Demolition and new construction while traffic continues

Facts and figures

Client:
Client: Federal Republic of Germany, represented by Autobahn GmbH des Bundes
Object:
Construction of a new bridge to carry the A1 over the L290 and cycle path in Ostholstein
Design:
Engineering team Trebes
Services:
Project planning
with BIM (civil engineering), structural design with BIM
Special features:
  • Construction in existing buildings while traffic continues
  • 14 different traffic management phases for each substructure
  • High geometric requirements due to the combination of a considerable skew angle of the structure and the alignment of the A1 as a clothoid with discontinuously changing cross slopes

Consequence of recalculation

In Ostholstein, the villages of Sereetz and Ratekau are connected by the L290 state road and cycle path. Since 1974, a bridge structure on the A1 has spanned the state road. A recalculation in 2018 revealed a limited load-bearing capacity and therefore classification in bridge class BK60. In addition, the superstructure was assessed as a continuous prestressed concrete slab with hollow sections as a high-risk construction method.

As the client, the FRG therefore decided to demolish the existing building and replace it with a new one.

From the preliminary investigation to execution

Several different load-bearing and cross-section systems were considered in the preliminary investigation. Ultimately, the single-span integral frame structure with an open steel composite beam proved to be the most suitable solution. The foundation could be designed as a shallow foundation, as the existing subsoil had sufficient load-bearing capacity.

The construction of the entire structure - consisting of 2 partial structures with a length of approx. 28 m and a total width of approx. 32 m - is planned for the period from 2023 to the end of 2024.