So, more brainwaves about unintended consequences:
Anything passing through a portal will stay Fringeworthy. A non-FW touching it would not turn off it's Fringeworthiness. Okay, so what's the unintended consequence of that? Well, if it's Fringeworthy, it can make other things Fringeworthy. (as long as a non-FW is not touching it. Have to have that exception in there.)
That means you can use this property on those automaton vehicles I mentioned. They roll up, attach to a cable or belt running into the portal and go on through. That completely automates the process, and may in fact, not need FW to run it. (They would need them to maintain it though, so it's a partnership of sorts.)
So why is that cable or belt running into the portal? Power generation, water or fuel delivery, moving items on the platform for use on the platform. Lots of reasons.
That's talk about this cable and belt.
The cable is more than likely just a metal cable of some sort, whose only purpose in life is to impart Fringeworthiness on unpiloted vehicles. So steel, probably coated in durable plastic, running between 4 pulleys, two on the platform and two on the world, looping around the ring.
The belt probably comes in various varieties:
For power generation on and off the platform, it's made from Kevlar imbedded with graphene and carbon nanotubes. 5 times stronger than steel. It runs through a set of gears on both sides of the portal. On the world side, it runs a generator generating power for the base, or at least the building housing the portal. When you're out exploring, it's your base camp power generation system.
On the platform, it's used to power all sorts of mechanical devices either through belt drives or shafts. We'll get into what it's powering later.
The other belt type is the "pipe" variant. In this case, it's flexible pipe that's slit on the top so that it can be filled with water, fuel. or other liquids. A spreader opens the pipe allowing it to be filled, then it closes up, with the slit on the top. Channels on the sides of the pipe run though guides keeping it upright. As it passes through the portal to the platform side, it rotates and another spreader opens it up, emptying its contents into a catcher system. Pumps powered by the other belt move the fluids around to where they are needed.
The other cable variant is just a modification of the simple cable. It has hooks on it, and it runs through the portal so that you can attach items to it and deliver them to the other side. It's not fast, but it's consistent.
So, all that mechanical power... What's it for? A whole lot of babbage controlled machines that either sort and move items around or to power automatons on the platform so they can move things about and load transport vehicles. The vehicles are steam powered, (simpler systems to maintain, even though they are the height of Steampunk Technology) so they have their water and fuel topped off. The platform automatons read the carriers attached to the engine, pulling off those for this platform, hooking up carriers for the direction the engine is going. This system is duplicated on all the platforms where necessary. (The Mars portal for UN Earth is also a destination for many goods and items. Got to keep Elon Musk's colonies supplied...)
The main unintended consequence is that the platforms are not empty, waiting for someone to show up, with a lone Fringe Security post, they are instead hives of activity, as carriers come and go, get routed to different portals, never a moment's rest.