With the four-lane extension Olten-Aarau (Eppenberg Tunnel), the Federal Government and the SBB are remedying one of the largest bottlenecks in the middle. The 855-million-franc project mainly comprises extensions in the Olten access road, a fourth, 2.5-kilometer-long track between Dulliken and Däniken and the two-lane, three-kilometer-long Eppenberg tunnel as well as comprehensive measures for its connection.
The project includes two technical buildings with transformer stations. Specification and tendering was done by Braavos. The station in Wöschnau is already in service, the station in Gretzenbach will be installed in 2018.
During the ongoing construction, the site is powered by six mobile transformer stations, specified and organized by Braavos.
Braavos has specified earthing concepts to separate the earthing of the local power companies and the railway and is doing supervision of the provisional grounding measures during constructions