Grouft Tunnel

2005 - 2010
Lorentzweiler - Blaschette


Civil Engineering

Grouft Tunnel

The centerpiece of the northern motorway.

The Grouft tunnel is part of the Route du Nord, and connects the Plateau Haeschtreferbierg in the south to the Vallée de l'Alzette in the north. It is 2,966 meters long.

It is made up of 2 separate tubes of unidirectional circulation.

The downtube towards Mersch has 2 lanes plus the exit ramp at the approach to the Lorentzweiler interchange. The tube to Luxembourg has been fitted with a third track for heavy goods vehicles.

The excavation was done by coming from the North and South sides of both tubes at the same time, in other words from 4 simultaneous fronts.






Shotcrete and surfacing concrete

Construction details

Details of the structure :

  • The width of the excavation is 11 metres for the 2-way tube and 15.5 m for the 3-way.
  • With regards to elevation, the tunnel has a maximum longitudinal slope of 4.63% from the portal of the ‘Vallée de l'Alzette’, ie a vertical drop of 130m.
  • Almost the entire length of the tunnel passes through forests and fields.


Félix Giorgetti was responsible for the following :

  • Platforms for the installation of construction sites;
  • Earthworks for the north and south entrances to the tunnel, including the reinforcement of the walls;
  • All road works outside and inside the tunnel.

Key Figures

Horseshoe shape and / or counter-vault

(3 lanes up / 2 lanes down)

2 parallel tubes 

Galleries at a distance of 300m each, of which 3 are suitable for vehicles


Operating buildings


Emergency bays at a distance of 100m each


Underground excavation length

2 x 2,966 m

Pavement width

7 to 10.50m

Useable width

10 to 13.50m

Typical excavation profiles

69.50 to 111.70m² 

Excavation volume


Concrete in the inner ring


Projected concrete of the outer ring


Rock bolts


Metal support


Underground waterproofing


Longitudinal slope

max. 4.63