The Belchen Tunnel on the A2 motor highway between Basel and Egerkingen crosses the Jura Mountains. The bedrock contains parts called Gipskeuper, a rock mass comprising anhydrite, hence causing damage to the existing tunnel lining due to rock swelling processes. Severe damages require rehabilitation of the two, dual carriageways tunnels.
The essential measures include:
- Extensive repair of the two tubes (including replacement of the invert arch,
renovation of the arched ceiling incl. securing its bedding, replacement of the
intermediate ceiling, refurbishment of the underground control centers,
adjustments to the ventilation system, to the drainage and other operational
and electromechanical equipment, etc.);
- New, additional cross passages between the two tubes;
- Filling of the existing shafts and dismantling of their cover structures;
- Installation sites South and Logistics Area North.
Lombardi is very pleased to execute the mandate of project author civil works for the phases project of intervention/detailed project, tender, construction drawings, execution/commissioning in the same JV as the previous phases.
The implementation of some "bridging measures" in the middle tube (1st step) is expected to take place in 2021 and 2022, while the repair of the tube towards Basel is planned to take place from 2023 to 2027. This will be followed by the 2nd step of the repair in the middle tube.
Rehabilitation of two double-lane tunnels, each 3.18 km long, dating from the 1960s. Replacement of the invert arch in swelling Gipskeuper and Opalinus clay. Replacement of the intermediate ceiling. Decommissioning and backfilling of 3 ventilation shafts, each over 100 m high. New construction of cross passages. Reconstruction of the 3 underground control centers, ventilation, MEP.