There is nowhere else in Switzerland where vehicles are stuck in traffic jams as frequently as before the Gubrist Tunnel. That means that traffic accidents are a common occurrence. In order to remedy this problem and diffuse the traffic situation for the future, the expansion of the northern bypass around Zurich has been approved and planned, and it is a key project for the FEDRO, Federal Roads Office.
Amberg Engineering AG has directed the AHB Engineering Association (Amberg Engineering AG, Meichtry & Widmer AG, BHAteam Ingenieure AG) working on the demanding new construction project already since 2005. Incorporating the disciplines of foundation engineering, structural engineering and road construction, Amberg Engineering is responsible for the project development and on-site construction supervision of the driven tunnel.
Our project team on site provides us with regular insights on their exciting activities as well as the current work progress. Take a look for yourself to see how far the project has already progressed.
The driven tunnel was begun with a ground-breaking ceremony on the Affoltern side in November 2017. A good deal has already take place there with more that 80 m of advancement in the crown. At present, the tunnelling is still being carried out with an excavator and a cutting unit attachment. However, it is anticipated that soon a switch will be made to drill and blast. The current rate of advance is about 4 m per day deeper into the mountain.
The new third tube includes eight man-sized and four trafficable cross-passages spaced at about 300 m which connect to the existing second tube. Moreover, there will be 25 combined SOS and hydrant refuges spaced at 150 m located on the outer side of the tunnel. Overall, three new control centres and two new ventilating stations will be constructed. There is a control centre and a ventilating station at each portal. Construction of the Sunnenrain subterranean control centre is planned at about the middle of the tunnel on the north side.
The design of this control centre is in progress and is being visualized primarily as a 3D model.
On the Weiningen side, the initial metres of the tunnel have also been dug by excavating under a 1.6 m thick concrete roof using the top-down method. In addition, the preparatory works for the re-routing of the Zürcherstrasse roadway planned for the coming months are in progress. The traffic will then be routed over the finished roof construction via a roundabout, thereby creating space for the next construction phases. The actual tunnelling in Weiningen is slated to begin in March. For this to take place, a pipe umbrella must be constructed first.
At the cut-and-cover site in Affoltern, the excavation and the associated revetment is being conducted at the same time as the tunnel construction itself with close coordination between the two tasks in order to avoid mutual obstructions. The installation site is also humming with activity: A second structure for accommodating workers has been constructed and the belt conveyor system and the crusher have already been installed.
The construction site’s own railway loading station for removal of the excavated material estimated to amount to about 1 million tonnes passed acceptance in mid-December. The first freight train loaded with spoil left the loading station at the Affoltern tunnel portal on 8 February. Over the next two years, it is expected that 2 to 3 trains daily will remove a total of 700,000 cubic metres of rock. This will avoid the necessity of about 160,000 truck trips.
Would you like to find out more about the Zurich northern bypass or see a bird’s eye view of the project? Then have a look at the FEDRO project video on the expansion of the Zurich northern bypass or take a drone flight over the Zurich northern bypass. Have a good flight!