Eppenberg Tunnel

The Eppenberg Tunnel is a railway tunnel in the Canton of Solothurn, Switzerland. It is part of the 'Future Development of Railway Infrastructure' plan and increases capacity on the Aarau–Olten line in the Schönenwerd–Däniken section. A particularly constraining bottleneck in the Swiss rail infrastructure is in the section between Aarau and Olten, which has only two tracks at Eppenberg-Wöschnau, Schönenwerd and Gretzenbach. The route has to be shared by international and national passenger trains as well as freight. Hence quadrupling the complete line between Aarau and Olten had high priority among infrastructure projects. The main purpose of the tunnel is to increase capacity. The two additional tracks in parallel with the existing double track line effectively create a four track line. The Federal Assembly adopted the law authoring the 'ZEB' programme in the spring session of 2009, authorising the budget for the Eppenberg tunnel.