Another problem is cart switching - there's no good way to filter carts with a switch without dwarves pulling levers (I mean a solution that makes steel bars from source A turn left at a switch, and stone from source B go straight ahead, automatically). The only way to do this is with pressure plates and weights, but that involves tedious calculations with every new cargo.
Well, this system is designed to do exactly that. You set one of the loading modules for steel bars to floor 2, another one for blocks to the surface. The switching logic takes care of the rest, no need to pull levers, manual labor is required only at the loading bay. In fact, the tracks on image 3 can be much simpler, the convoluted web of track that surround the staircase are not necessary, as long as you send the cart from the blue exit to the blue entry point it will find it's way back as long as the bottom and the top of the helix is connected in a loop. They are there to shorten the hauling route, so your cart doesn't have to make a full cycle to the bottom/top before returning. Complexity for the sake of speed. If your helix is like 40z level high, you're better with a simpler design, but with 120z levels to travel (twice!) those extra tracks can speed up the process.
I did some research on the workflows too, and my conclusion is that 8 loading station is more than enough to to transport away all the possible product from a burrow, and none of my burrows would have more then 6 (different) incoming raw materials. For example one route is enough to transport the flux stones and ores to the magma smelters, one for sand (clay), one goblinite, one for food and one for clothing. Outgoing routes would be weapons, blocks, trade goods, bins/barrels and maybe furniture. A strip mining floor would transport ores/flux to the smelters, and gems/stones to the crafters, so that's only 2 routes...
A lot depends on how you build your burrows, and where you put your workshops. Like does the cloth industry go to the food section to be close to the pig fiber industry, or do you choose to put into the crafting floor, and work on a silk farm? These details matter...
What do you think about adding a pressure plate at the loading stop that triggers a timer when the cart gets pushed en route? When the cart gets close to it's destination, the timer opens a sidetrack that leads to the output stop. A pressure plate at the beginning of the sidetrack opens another sidetrack that will lead following minecarts around and back to the main track. After a hundred ticks, both sidetracks close, leaving only the main track.
Of course, the timer would need to be very precise and the lower sidetrack would need to have the same travel time as the main track. A lot of work but it could give you a super efficient track system.
First problem I see is that if you have more than one cart in the system, you cannot know which cart will reach p1 first. If your full-to-the brim magma cart reach your booze dumper first, you're going to have a "slight" problem.
Weight adjust p.plates are only possible with empty carts, as there's no way to know the exact weight of a full minecart. A notable exception is a magma/water filled cart, so these routes
MUST have weight adjust pressure plate separating the loading/dumping sections from the rest of the track system to minimize !!FUN!!.
It may be possible to make timers which open the sidetracks at exactly the right moment, but all the hauling routes will need to have a custom timer prebuilt. And if you have such a timer then sidetrack are not necessary: you just have the timer active the dumping station at the right moment.
However building a timer THAT precisely is out of my league.
The most precise timing is possible with gears/rollers: one plate switches it on for max. 100 ticks, and you can have another plate switch it off without delay. But you cannot get rid of the 100 ticks reset cycle, as when both plate reset you'll get a "phantom signal", which has a chance to screw with you.
Inspired by this idea, here's a rough mockup of an alternate design to the loading station: Instead of doors, this one uses powered rollers to pull/push the cart from the track into the station. G0 is always on, G1 is activated by LOOPSYS, and G2 is switched on with PP5, and switched off with PP2. PP5 is weight adjusted, so only the desired empty cart activates it. If we want to build a system which can have more than one active cart inside, this provides much faster switching, and doesn't block the main track with a closed door like the previous design.
But the main problem with having more then one cart is to do with dumping, not the launching sequence: You want to link your quantum dumps to your regular stockpiles, so you dwarves won't try to haul the contents back to the destination burrow by hand. Even if you confine you dwarves into burrows, you need extra haulers that can access any part of the fortress, and the masons and miners need to go anywhere too. That means, if you have a bad dump (for eg. wood got dumped into the ores stockpile because of a timing error) it will sit there, no dwarf will touch it because the linked stockpile won't accept it. That is only annoying, but things will start to get interesting when you manage to dump magma into a food stockpile, or a cart full of adamantine into a magma reservoir...
A possible solution is what I mentioned in my previous post: max. 2 carts in the system, one empty, one full, and only one active dumping trackstop. The sequence is almost the same as before, but you have a weight adjusted plate after the dumping station that triggers on the empty cart launching another full cart.
Complication no1: The changeover switch can only handle 2 states, so different logic is needed with three states:
full en route (Dx, Dy OPEN, TS1 ON, LOOPSYS OFF)
empty returning (Dx, Dy OPEN, TS1 OFF, LOOPSYS ON) -» second cart can launch
empty@home (Dx, Dy CLOSE, TS1 OFF, LOOPSYS ON)
I tried designing one with minecart logic, but couldn't come up with anything that uses less than 4 carts. That's 2 newton cradle just to build one hauling route. Not worth the trouble when you need to build at least 15-20... Fluid logic can be a solution, but I'm no expert on those. Plus building that many connections is PITA.
Complication no2: Suppose you have two active routes at the same time, and both of them return to the same floor. That means SYS1 and SYS2 will both want to open the same door (Dm). But when SYS1 is deactivated, it will close Dm despite SYS2 still needing it, so cart2 will get stuck in the system without a valid route back. Plus it's the same with LOOPSYS: both routes will want to keep it switched on, so you need a huge AND gate. (3 gears x number of routes)
(Or do I overcomplicate things, and will SYS2 be able to keep that door open despite it receiving a CLOSE signal? If yes, then ignore this. Although I have a few ideas on how to solve that, but I'll let it rest for now.)
Complication no3: Every hauling route must have a cart with
unique weight. So unless you want to start modding the density of materials, you are limited to how many hauling routes you can have. I have not counted how many carts are possible, but the fact that iron is the same weight as steel means you have less then optimal solutions.
Damn, that's a long post. I guess I'll stop now.