The start follows months of delays due to problems experienced in the preliminary access tunnel lot. Construction of the US$105m station shell contract is being undertaken by Marti and includes the excavation of two 330m2 caverns of 213m length; plus various cross passages, shafts and galleries. The designer is RBSverbindet with Emch+Berger.
Excavation will be mainly by roadheader, mining around 144,200m3 of rock. Support will be by shotcrete (around 18,500m3), rockbolts and in-situ concrete.
The north logistics cavern will be excavated first to accommodate the fixed installations (transformers, dust extractors, escape refuges, etc.) in the underground area. Once this has been excavated, the Marti team will begin with the cross passages of the north cavern and the south logistics cavern. For space reasons, the logistics cavern is excavated with an excavator, the cross passages with a smaller roadheader, and the platform caverns with two large roadheaders.
Excavation will be in a geology comprising mainly sandstone, fine sandstone, siltstone and marl. April 2021 will see the installation of the conveyor belt to take spoil from below ground to the loading facility, from where it will be transported to landfill sites. In the meantime, spoil will be lifted out using a tower crane and buckets.
Work is expected to be completed and the station shell handed over to the client Regional Transport Bern-Solothurn (RBS) in August 2026; this will be followed by systems’ installation in the four new underground tracks.
