The Leipzig City Tunnel goes underneath the centre of the trade fair city from Bayrischer Bahnhof to the main railway station. The City Tunnel involved the new construction of four underground stations and a single above-ground station. The City Tunnel was commissioned in December 2013. The City Tunnel involved the new construction of four underground stations and a single above-ground station. The City Tunnel was commissioned in December 2013.

The City Tunnel is made up of two single-track tunnel segments (length 1,438 m), which were constructed using a shield tunnelling method.

The services provided by SIGNON included consultancy and supervision for the implementation of plans for the overall earthing plan (GEK) for the Leipzig City Tunnel (CTL). With regard to the consultancy and supervision required to implement the overall earthing plan (GEK), the Project Engineers commissioned by DEGES responsible for the structural work planning and spatial expansion were given support in relation to the internal earthing and equipotential bonding. With regard to the consultancy and supervision required to implement the overall earthing plan (GEK), the Project Engineers commissioned by DEGES responsible for the structural work planning and spatial expansion were given support in relation to the internal earthing and equipotential bonding.

The results based on an analysis of the local situation, the tunnel project and the existing rail systems then fed into an updated overall earthing plan (GEK).