The City Tunnel project in Leipzig is one of the biggest inner-city infrastructure projects anywhere in Germany. It is part of a large-scale rearrangement of the entire railway system in the Leipzig metropolitan area. In order to deal with the high slab loads and to reduce repositioning times, the Doka heavy-duty supporting system SL-1 was fielded here. Following completion of blocks 36 - 37, most of the items used here were re-used on the tunnel slab traveller for blocks 38 - 44.