No, no that's not normal and it's happening again and again with greater frequency before Beauford has a look of realization. Those thuds sound like something running towards them and he's starting to yell as something that looks like the bastard child of a mutagenic threesome of a lobster, octopus and Godzilla crests over the side of a hill to the side of the trolley car.

"GET DOWN AND GRAB SOMETHING SOLID!"