The Sky train track between terminals 1 and 2 and the national and regional train stations at Frankfurt International airport.
The trains are driverless and run on rubber wheels on segregated tracks, with a third-rail style power source. This photograph is looking towards the railway stations station from a train en-route from there to Terminal 2.

Photo by Chris McKenna 08/08/2005. Larger, higher quality copies of most of my pictures are available, please email if you want a copy. #cmckenna@sucs.org