I think they're cloaks, which are basically just blankets with a clasp so you can wear them. Capes are shorter, lighter, and often hang from other clothing as a decoration.

I had to look up the distinction to confirm it, and they seem right on the border as far as length goes, but if they're actual kit and not just part of the dress uniform they're probably pinned up to knee height to avoid tripping anyone. They may also be folded and pinned horizontally to make them narrower and less unwieldy, since it looks like they're wider than how they're hanging.