Escalators and Moving Walks

I was fascinated by an image I found on flickr, showing a person standing still on a moving walk, while the world was flowing by. The inspiration has led to these images. One from the Gardermoen airport, with the camera on the moving walk, and two from the west escalators at Nationaltheatret train station.

You must set your focus distance manually first. It seems to me that a typical good shutter speed is 2-3 seconds, and the trick is to hold the camera steady on the rubber hand rail. i haven't tried using a tripod on the walk itself but wouldnt put it past me :-)