Abstract: A flexible buffer transport system for staging accumulated documents for transfer to a synchronous downstream transport. Control of movement of accumulations in the buffer being independent of the length of the documents. The system includes a plurality of roller nips in series. The roller nips are spaced a uniform distance apart. Each of the roller nips are driven by an independently controllable motor in communication with a controller. Position sensors also communicate with the controller. The sensors sense positions of lead and trail edges of accumulations of documents within the buffer transport system. For each sampling period in the operating cycle and for each roller nip, the controller determines motion control. First, the controller determines which nips should be slaved together based on which are needed to control a particular accumulation of documents under its control.