A westbound London Underground 1992-stock Central Line train climbs out of a tunnel to platform 3 at Stratford high-level station, en-route to Ealing Broadway on 24 October 2005.
A gap in the third (far) and fourth (middle) rails that carry +420 and -210 volts respectively can clearly be seen. This is a current section gap, enabling the power to be turned off on parts of the line without affecting the rest of it.

Photo by Chris McKenna 24/10/2005.
Larger, higher quality copies of most of my pictures are available, please email if you want a copy. If you wish to use this, or any other of my photographs, under a different license see my relicensing policy. #cmckenna@sucs.org.