Eppenberg railroad tunnel

The four-track ex­pansion of the Swiss federal railways SBB between Olten and Aarau is a crucial part of the ex­pansion of rail capacity for freight and pas­senger traffic in Switzerland. The heart of this project was the con­struc­tion of the new double-track Eppenberg tunnel between Däniken and Wöschnau. The Marti Eppenberg con­sortium built the tunnel, which spans more than 3 km, under geo­logically and hydro­logically chal­len­ging conditions