I know I’m not the sharpest tack in the box, but as I was watching the guy work, I realized they still have to seal the other end of the tunnel.
Er, right?
Or would they skip sealing since that will be under the walkway?
Are you referring to this part of the tunnel?
If so, that is part of the original tunnel and was not painted before (and didn’t need to be waterproofed).
Using google street view, here is the original West end of the tunnel. None of it is painted except above the doorway.
Here is the original East end of the tunnel with the retaining walls painted.
I think the new extension on this end will be painted inside to match the old retaining walls (and therefore why it needs to be waterproofed). Hope this is helpful.