Hi
As Dave said, I cleaned (redid) the geometry first (using the axes for the circles or arcs), then clarified the dimension of the inner arc to adjust the texture size exactly to this dimension, assuming that's your intention (?). In addition, I separated the outer concrete shell from the inner (to become painted) surface to get easier access to this face. For texturing I used Fredo6´s ThruPaint plugin then.
To make this entire procedure much easier, this can happen at a short section instead of the whole length of the tunnel 😄
Tunnel Test HX.jpg
Tunnel Test HX.skp
