Siemens Combino

[1] Due to its modular design using standardised components, and the resulting reduced costs, the Combino was for a time one of the most successful tram types.

Subsequently, the model was again renamed and is now known as the Avenio M. The original Combino trams were a multi-articulated design with alternating wheeled and suspended sections.

The tram is largely made out of aluminium, with a welded underframe to which the body framework is bolted in sections,[1] which means that the Combino can easily be adapted to different lengths, widths and gauges.

For Nordhausen, three Combino Duo trams were built with an additional diesel propulsion system,[5] courtesy of a BMW M67 3.9-litre twin-turbocharged V8 engine.

[7] The torsion forces produced when the tram travelled through reverse curves were much higher than anticipated, leading to cracks around the articulations between modules.

[4] Subsequently, hairline cracks were found in the joints of the aluminium bodies, which could cause the roof to collapse in the case of an accident.

Cracks were reported on the connections between the sidewalls and the roof girders such that the safety of passengers in the wheel-less modules could not be assured in the event of a severe collision.

These flaws were reported in many cities that had adopted the Combinos, such as Düsseldorf, Freiburg, Augsburg, Erfurt, Hiroshima, Nordhausen, Basel, Potsdam, Bern, Amsterdam and Melbourne.

Earlier, Siemens technicians had identified stress fractures in the door segments of two of Amsterdam's oldest cars.

Poznań ordered 14 trams, each consisting of five modules, three double doors and three bogies, identical to the Amsterdam version.

An agreement between Poznań and Siemens provided that the city would pay the fraction (31%) of trams' cost only after the refit of all 14 Combinos.

Siemens also expressed a desire to sell the Viennese Ultra Low Floor (ULF), another 100%-low-floor model, to other cities.