 Poor construction, the theft of necessary iron reinforcements and several ground water break-ins into the tunnel, which were not reported or controlled properly by the construction company, are among the alleged causes for this catastrophe.To make use of the already completed tunnels and stations, a shorter service running from "Dom/Central Station" to "Rathaus" (city hall) started operation in December 2012, re-routing Line 5 from its previous terminus at "Reichenspergerplatz" to serve the new NSS.A further expansion to "Heumarkt" opened in December 2013.