How do I properly texture a tunnel?

I took a look at the 2fort tunnels and found that although they used the same texture each non-nodraw face of each chunk of the tunnel involved plenty of texture shifts.

But the problem is that I don't see a pattern to the texture shifts. I know that the end result is that they seamlessly blend together, but that doesn't help in getting to that end result.

Ok and I also see that there are two well disguised seams at the top of the tunnel, I think I know what to do now.