At first I thought that you were standing on a track (not a good idea) then I realized you were probably on the back of a train and that is what gave the motion. I could be wrong. But I do get that queasy feeling you get when riding backwards at high speed.
@pistache tx Clare... zero magic involved here... i was in the last car of the subway as it was moving, with the camera pressed up against the back window... using a comparatively slow shutter speed... :)