Added Brick Texture
I found that for the bricks were slightly too big
Re-adjusted Brick Texture
I thought that the bricks were too bright and looked new but they needed to be dull and dirty to fit into a sewer surrounding
I found a problem that due to using repeat UV's when texturing, there was a line going along the roof of the tunnel.
Removing Repeat Uv's
This made the bricks really big so I knew I had to go and redo the texture.
Testing Idea - Rotating Texture and Adding Arch
I redid the texture by making the brick image smaller and repeating the brick pic over the Uv's.
I feel that the bricks going along the tunnel rather than round the tunnel does not work but I think arches could work and I may include arches at a later date when refining.
Finished (For Now)
So I rotated the brick texture back round and added in some lighting in the form of long, thin area lights.