Re-entered a tunnel for better pictures and less chaotic urbex safety

I recently posted about going on a walk into a tunnel. Well, I went back into the tunnel recently with a different group of people, but this time I was "in charge" and my safety rules were the ones we were using. It was a much better experience! With fewer people and less chaos I was also able to take the time to take better pictures. Here are some of those pictures. Warning: the final picture is an image of two roaches sitting right next to an itty-bitty bat. If you don't want to see a fairly large image of either of those things, do not navigate past the picture of barn swallows. An incredible muck deposit which has calcified(??) over the years, then got graffitied. It's the best art in the tunnel, but the tunnel is so narrow that it's difficult to photograph. In general you find that the tunnel is full of the kind of political or ideological graffiti you never see above ground. I strongly believe that people come to write their heart's true cry in the tunnel because the tunnel is…