The rider, a 33-year-old man from Huntingdon, was seriously injured in the crash on the slip road to the northbound carriageway of the A1 at 9.25pm last night (Monday). He was taken to Addenbrookes Hospital, in Cambridge, in a critical condition. The slip road was closed until 1am while an investigation was carried out and recovery of the Honda motorbike. Pc Simon Burgin is appealing for witnesses. He said: I would appeal to anyone who saw the collision, or the motorcycle prior to it, to call police. Im particularly keen to speak to another motorcyclist who stopped at the time of the collision as they may have information which could assist our investigation. INFORMATION: Anyone with any information should call PC Burgin at the Roads Policing Unit on 101.