STRABAG widening Germany’s longest motorway viaduct to eight lanes

• Consortium of STRABAG Subdivision Bridge Construction and Subdivision North to widen and rehabilitate the Hochstraße Elbmarsch A7 motorway viaduct (K20) in Hamburg

• Contract awarded by German motorway planning and construction company DEGES worth over € 200 million

• Work on the nearly 4 km long motorway section to be completed by 2027

The STRABAG Group has been awarded a large contract in Hamburg. Cologne-based STRABAG AG was commissioned to widen the Hochstraße Elbmarsch (K20), a section of the A7 motorway, from three to four lanes in each direction. At 3.84 km in length, the elevated motorway section is the longest road viaduct in Germany. The DEGES contract with a volume of more than € 200 million is being carried out in a consortium of STRABAG Subdivision Bridge Construction and Subdivision North.

Advertisement

The elevated Hochstraße Elbmarsch section of the A7 motorway begins a few hundred metres after the exit from the Elbe Tunnel heading south, passes over Rugenberg Port, crosses two railway lines and eleven roads and paths in the Hamburg city limits, and ends at the Hamburg-Hausbruch motorway exit. Construction is scheduled to be completed by the end of April 2027. STRABAG is currently carrying out the detailed design; at the same time, work has already begun on site installation, demolition and removal, and deep foundation.

Objective: Improved traffic flow on central north-south link

“We are delighted to have been awarded this major German infrastructure project and are gratified by the confidence placed in the capabilities of our infrastructure construction teams. The widening of this busy section of the A7 motorway will improve the traffic flow on Germany’s central north-south link in the long term,” says Thomas Birtel, CEO of STRABAG SE. The daily volume of traffic on this section of the A7 motorway has increased to between 50,000 and 60,000 vehicles in each direction since the construction of the elevated road 45 years ago. STRABAG Subdivision Bridge Construction (Business Unit North) and Subdivision North (Business Unit Specialised Construction) are currently proceeding with the planning and site installation works for the motorway widening and general overhaul. At the same time, upstream maintenance work on the underside of the existing elevated road are continuing until the end of the year. These works are also being performed by a team from the STRABAG Group: ZÜBLIN Structural Maintenance (consortium leader) and Subdivision Bridge Construction have been jointly renovating parts of the substructures and exchanging the bridge bearings since the end of 2018.

Widening under traffic

The option to widen the viaduct had already been planned for and prepared when the elevated road was built in 1975. The foundations in the port area and the connecting reinforcements on the inner sides of the bridge superstructures, structurally separated for both directions of travel, can now be used for the planned upgrade. The fourth lane will be added to the inner side of each viaduct, bringing the two sections of the A7 motorway closer together. Traffic is to be disrupted as little as possible during the construction work. The widening will be carried out in steps to allow traffic to continue to flow along three lanes in both directions at all times. The upgrade will begin on the carriageway in the direction of Flensburg (north), with work scheduled for completion by mid-2024. This will be followed by the start of the second phase, the widening to four lanes of the carriageway in the direction of Hanover (south). Three further STRABAG Group entities are also involved in this project: STRABAG Business Unit Hamburg (road construction), Züblin Stahlbau GmbH (steel girders) and Zentrale Technik Hamburg (planning).

A few key figures on the material requirements provide an insight into the dimensions of the project. The widening of the Hochstraße Elbmarsch elevated road will involve the use of around 19,200 m³ of concrete. In addition, 15,000 m of steel railing will have to be renewed. The rehabilitation of the roadway will require the removal of asphalt and waterproofing over an area of 135,000 m² and the laying of new asphalt over an area of 155,000 m².