One consequence of the modification of the Volksbank building in Böblingen were changes underground. Therefore, IWR GmbH and Gera-based engineering office Köhler were tasked by Eigenbetrieb Stadtentwässerung Böblingen with the planning and construction supervision of a culvert (a pressure line to underpass a road, for example). A special feature of this culvert: in the case of dry weather sewage is pumped exclusively, and only when it rains the combined culvert starts to operate. The manholes at culvert entrance and outlet were executed in PE.