After being kicked off the train at Guildford this morning, due to signalling issues, I came across an "OsmaDrain Rodding Eye".

What the hell is a Rodding Eye?

EDIT: Found out what it is when I got to work and looked it up.

rodding eye Also found in: Acronyms.
1. A pipe fitting with a removable plug which provides access for inspection or cleaning of the pipe run. Also called an access eye or cleaning eye.
2. An opening at the base of a chimney, stack, or breeching for the removal of dust, soot, etc.
3. An opening in concrete forms for removing debris; closed before the concrete is placed.
The Free Dictionary