Maintenance

All of the tunnels outside of the main halls are probably maintenance. This is the most common access on the station, though not completely ubiquitous, and the area is marked by its proximity to every other area, its poor lighting, and its exposed pipes. Perfect place to get attacked!

Hide and Seek

These are usually safe, and full of gear that would otherwise be completely restricted like sunglasses, gas masks and even backpacks. If you see something in the maintenance tunnels that doesn't look right (OMG BLOOD IS EVERYWHERE), inform the detective as he's the only security person with maintenance access besides the Head of Security who really shouldn't be that far from the brig. It is possible to disappear on purpose in the tunnels, but hiding requires you to go really deep into the station's bowels to escape the eyes of security and crew. The AI will often kill people in maintenance when rogue and, if need be, hide the bodies with a cyborg.