The expansion/new construction of the railway line "Hanau-Würzburg/Fulda-Erfurt" is one of 13 infrastructural projects of the Deutsche Bahn AG that are to be implemented with high political priority. The new DB-Line Gelnhausen-Fulda is a sub-project of this infrastructure project with a section of approximately 42 km (variant IV) respectively 48 km (variant VII) and hence, the planned construction of up to 80 percent of each variant in a tunnel. From a geotechnical point of view, two route variants are examined in detail regarding feasibility of the tunnel construction and taking hydrogeological and natural aspects into account. Both variants have a very high impact and require very different requirements on the planning and selection of suitable tunneling methods. In this article the relevant geotechnical, geophysical and rock-mechanical investigations and findings are presented in detail as the basis of the decision-making process in finding the most economical and operational suitable route variant.
The line between Hanau and Fulda is an important and intensively used railway line. Due to the congestion of the railway line, which is currently used by up to 300 local, long-distance and freight trains per day, the Gelnhausen - Fulda extension/new line project is intended to solve existing bottlenecks and to increase the existing capacity (see Figure 1). Furthermore, the new line is expected to significantly shorten the journey time for long-distance traffic.
The new line (red marked in figure 1) is subdivided into three sections: the upgraded line Hanau - Gelnhausen and the new lines Gelnhausen - Fulda and Fulda - Gerstungen. Concerning the new line Gelnhausen - Fulda, two potential routes between 44 km and 48 km long (variants IV and VII) were selected from a large number of variants for the section of the NBS, on which a subsoil investigation is being carried out in parallel to the ongoing regional planning. The subsoil investigation campaign is structured in several stages. On the basis of the findings from the as-built documentation and the investigations of planning stages 1 and 2, a reliable and profound decision is to be made on which of the variants should be object to further investigation, planning and construction.
