White markings of RR and NB on BT manhole locations

Last weekend I noticed that suddenly there were white markings on BT manhole locations. These seem to be on every BT manhole cover in the surrounding area not just on my road. The only recent activity was a highway maintenance van with someone down one of the manholes last weekend, didn't see BT engineers.

Any ideas what "RR" and "NB" might mean? They are marked around all the BT manhole locations in the surrounding area.

I checked one.network and there wasn't any information going up to 12 months in the future, although I know they've recently changed access rules for the general public so wondered if it might not be showing up.

While it might not related Cadent are also in the area doing gas works.

Will get a picture if it helps!

Thanks

Edited by jamesmacwhite (Thu 18-Mar-21 22:04:27)