The new Munich link for the InterCity Express, Germany’s version of the French TGV, has not been easy. Extensions have been needed for the contracts between Nuremberg and Munich. Cost changes will take a $1.8bn project to at least $2bn.
The new-build section of the line begins just after an initial 11km length of standard speed suburban line out of Nuremberg. New-build high speed track then runs 78km south to the university town of Ingolstadt on the Danube itself, with two stopping points at new stations now under construction.
For the latter and more densely populated landscape onwards from Ingolstadt towards Munich there is only upgrading and widening of the existing train corridor taking place.
New work includes ten major tunnels, seven of them bored and three cut and cover and only two of them less than a kilometre in length. The North Section, running for 35km has been carried out by a joint venture between contractors Bilfinger & Berger and Max Bögl, and has gone reasonably well. It includes the 2287m long Göggelsbuch tunnel and the open cut Offenbau at 1331m long. But work on the Offenbau tunnel, a 1331m long section has been delayed because of an unexpected second water table. An open cut method has now been changed to mining using compressed air.
After Hochtief‘s central section comes the Southern Section which also has problems. It too has a long tunnel with karstic problems, the 3289m long Geisberg which DB has also ordered be investigated. Investigations have also been required for some cuttings and embankment in the Köschinger Forest because they run across the limestone and may have hidden subsurface voiding.
The contractor, a six firm group including August Reinersbau, Berger Bau, Alfred Kunz, Linke Tiefbau, Schälerbau Berlin and Heinrich Klostermann, has also seen cut and cover tunnel work and cuttings affected by discovery of "fossil slides". These are embedded slip surfaces between geological layers in softer Quaternary deposits of mainly clay and loam. Just 2m into excavation a number of ground slides occurred. Geotechnical investigations revealed the old slide surfaces and led to a redesign of cutting method using a secant pile wall up to 30m deep to support the cutting slope bases.
