SIKU Timeline Articulated Bus 100 Years SieperSIKU Timeline Articulated Bus 100 Years Sieper. A century in images Articulated buses are used above all in conurbations and cities in order to carry large numbers of passengers on busy routes and at peak times. To celebrate its 100 years anniversary, Sieper is introducing a MAN articulated bus in a limited quantity. Milestones in the company history are presented on the bus: an eventful century in images.