Motorway A7, 6-lane extension, protection tunnel Schnelsen

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Tunnel with a rooftop

connecting people

The A7 is the longest German motorway and an important European north–south connection. An upgrade of this motorway in the city of Hamburg was necessary to increase its capacity. GRASSL’s contribution to this upgrade is significant. The noise protection tunnels to be built in Schnelsen and Altona allow the two districts that were separated by the construction of the A7 a long time ago to be reconnected. And the best thing: the rooftop of the tunnel lives! New green and leisure spaces invite people and animals to linger.

paving the way

In inner-city tunnel projects which involve many planners, stakeholders and other concerned parties, communication is the key to success. The real challenge, however, is the design of the deep foundation of an integral structure in an area prone to the formation of sinkholes. The GRASSL team has been able to develop sustainable solutions for this complex engineering task – due to the team members’ high qualifications and transparent and collaborative communication.

creating construction culture

The tunnels themselves are simple structures, robust and low-maintenance without asking for attention. They add value for the residents, fauna and flora: green spaces, small gardens, recreation, water retention, less noise and congestion and much more. That’s forward thinking. That’s sustainable – possible even in infrastructure upgrades.

Year of completion


Type of intervention

New construction

Contracting authority



Bundesrepublik Deutschland



Type of structure

Road tunnel

Construction method

Milan method

Total length

550,00 m

Construction width

38,80 m

Construction material

Reinforced concrete

Services Grassl

Basic assessment, preliminary design, detailed design, planning for approval, preparation of tendering, construction supervision, technical examination

Services provided by engineering consortium

Latest news about the project

Inauguration of the Schnelsen noise protection tunnel

After five years of construction, Hamburg's Transport Senator Michael Westhagemann …