URBAN operators in Potsdam and Basel withdrew their fleets of Combino trams on March 12-13, after Siemens Transportation Systems confirmed that bodyshell problems were emerging at high mileages.

On March 1 Siemens revealed that high torsion forces in the articulations of cars with longer bogie centres were damaging the bolted aluminium bodyshells. The company shipped a Freiburg car that had run 215000 km to its plant in Praha for detailed examination. This found cracks in the connections between sidewalls and roof girders, such that the safety of passengers in the wheel-less modules could not be assured in the event of an extremely severe collision.

On March 12 Siemens advised operators to take out of service any Combino that had run more than 120000 km. As well as Potsdam and Basel, the oldest Freiburg, Augsburg, Erfurt, Nordhausen and Hiroshima cars were affected, together with the oldest NF10 cars in Düsseldorf. The Bern, Amsterdam and Melbourne fleets had not yet reached the cut-off mileage.

Siemens is examining the various cars to establish how to deal with the problem and advise the operators. With more than 400 cars in service, the rectification cost is expected to be substantial.