The Belchen Tunnel on the A2 motor highway was built in the 1960s between Basel and Egerkingen. 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 and renewal of the two tubes including replacement of the invert arch, renovation of the arched ceiling incl. securing its bedding, replacement of the intermediate ceiling, adjustments of drainage and ventilation system and other operational and electromechanical equipment, etc.; - New, additional cross passages between the two tubes as well as refurbishment of the underground control centers and cross passages; - Filling of the existing shafts and dismantling of their cover structures. The implementation of some "early measures" in the middle tube is expected to take place in 2022/23, while the repair of the tube towards Basel is planned hereafter. This will be followed by the final repair in the middle tube. After completion of the project, the outer tunnel tube will serve the traffic in the direction of Basel, while the central tube will become a maintenance and rescue tube. Lombardi is pleased to carry out the mandate of project author civil works for the SIA construction phases 32-53 (measures project to commissioning/completion) in the same engineering JV as in the previous phases.