Cool finds, thank you for documenting these. I'm pretty sure the valves are for a side mission on that level but can't say for sure since it has been a while.

Years ago, I had a theory that if subway level is entered early, subway mission begins therefore skipping everything before that. I really want to test it, maybe by using CE or some save file fiddling.

Cool softlock during badlands practice http://www.twitch.tv/banzkux/c/4373990