You must of been out shooting with the other guy in this challenge. I like the close up but this also looks a little flat on my screen as well. Looks like it was an overcast day. IMHO, I would play with curves or levels.
I like the way the track leads through to the light at the end of the tunnel. I like the processing an angle on this image better than the other image of the same tunnel :)
If this is the upper tunnel where's the lower one? Just kidding. Maybe waiting til a train started to enter the opposite end would have made this better adding value to the danger sign.