Projects

Grouft Tunnel

2005 - 2010
Lorentzweiler - Blaschette

Category

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.

2,966m

Lenght

800,000m3

Excavation

170,000m3

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

10

Operating buildings

3

Emergency bays at a distance of 100m each

62

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

800,000m3

Concrete in the inner ring

75,000m3

Projected concrete of the outer ring

70,000m3

Rock bolts

100,000

Metal support

11,000t

Underground waterproofing

190,000m2

Longitudinal slope

max. 4.63