THE PROJECT to build a cross-city tunnel between Leipzig's Hauptbahnhof and Bayerischer Bahnhof serving two intermediate stations is on course for completion in 2011.

Work continues to drive two bores over a distance of 1·4 km under the city centre using shield tunnelling (RG 2.05 p93). On June 19, the first stage of tunnelling between Bayerischer Bahnhof and Wilhelm-Leuscher-Platz was completed, a distance of 600 m, and by September 17, a tunnel boring machine named Leonie had begun excavating the 400 m stretch from Wilhelm-Leuschner-Platz station to the site of Markt station. The TBM is making its way north towards Hauptbahnhof, where it is expected to emerge in the spring. New sub-surface platforms are to be built at both Hauptbahnhof and Bayerischer Bahnhof, which has not seen any trains since 1992. At surface level, the protected station building will remain in place.

Once Leonie arrives at the northern portal, it will be dismantled. The cutting head will be removed and transported on the surface back to the site of the first shaft at Bayerischer Bahnhof, while the rest of the TBM will be hauled back through the tunnel. The second bore will then be excavated in the same fashion as the first. Tunnelling is expected to be complete by the end of 2010.

A system of stability monitoring that uses thousands of sensors to detect movement in the foundations of buildings above the bores is being employed for the first time in Germany. The system enables concrete to be injected from 15 shafts along the tunnel alignment to fractionally lift or realign foundations.

At 2003 prices, the tunnel project is expected to cost €571·2m, with the largest financial contribution of €194·8m coming jointly from the Sachsen Land and the city of Leipzig. Initially the tunnel will be used by local S-Bahn and Regional Express services, but in the longer term, inter-regional and inter-city trains are also expected to pass through, although these will only call at Hauptbahnhof.