What's bothered me about hulk is that there is a hitch in the track before going into the loop. U feel a jolt like the track is slightly uneven between two connecting pieces. I've noticed it for a while now. Maybe they are actually fixing that assuming that's what has been causing that.
They actually replaced a section of the track pipe in that area sometime in the past 5 years. Regarding the shutdown right now, I have never seen them wall hulk off like that. It must be an intense bit of plumbing that they are embarking on. Hopefully we will get additional pictures of the work progressing and a better idea of what exactly they are working on.