5 Drives with 26 Curves Built in Zug, Switzerland; Lessons Learned

摘要

The sewer system in the city of Zug, Switzerland is finished with a new surface water discharge line of 79 inch inner diameter consisting of 3 microtunnels with lengths of 2,894 feet, 1,932 feet and 1,187 feet. Further on the city planned to use the lake’s water for heating and cooling purposes, which requires 2 additional 63 inch inner diameter drives which run next to the surface water line in a distance of as little as 4 feet. These 5 drives were built with 8 vertical and 18 horizontal curves to get around the obstacles in the ground and to place shafts at the least disturbing locations. All drives are located under roads with heavy traffic in the middle of the inhabited city.The construction period for the drives was from September 2017 to May 2018 including 2 stops and rescue pits. The tunneling work was carried out 24 hours a day, 7 days a week. This to keep the disabilities in the city center as short as possible.As a result of the size of the project, the boundary conditions and the very tight deadlines for execution planning and implementation, new tasks were constantly arising. This paper discusses the lessons learnt through designing and executing by the perspective of an engineer. Risk management, rolling planning, ensuring the required quality, cost monitoring and cost forecast, time schedule and technical challenges are the main points. The lecture should inform about risks and mistakes and give recommendations for upcoming projects.