Today I made lots and lots and lots of traffic...
But also, I experimented with this...
My City has 2 main line rail lines off map. I've also got an internal rail network that connects dedicated industry areas that can effectively only really export (via Ship, or Air hubs). Every time I link the internal rail network with the external one, it gets ****ing swamped with traffic.
So, I thought I'd try and build a rail-only hub. The main rail cross-roads on the left connects the North/South and East/West outside connection routes. This is laid out so trains never have to cross incoming traffic. Off that, I took an in feed and out feed from/to the north, south, east and west lines, and fed them to the uppermost cargo station in the screen shot. Again, doing it with eight separate connections means traffic in one direction never crosses the other, this is vital for high capacity rail networks... then the bottom two cargo stations in the screen shot are fed by a single spit line in, which is the end of the internal cargo rail network.
So.. the internal trains come in, the trucks leave the cargo hub with my industry export cargo, and follow a one way clockwise route, that twists and turns underground, then feeds back up to the external hub... and the returning trucks then go through a couple of traffic spirals back to the incoming station. I kept adding to the length and adjusting the speed limit on the roads down, until the traffic flow between the two, even with 2 loco's in and 1 out in permanent use, became pretty much constant. Crucially there is NO road connection from the this rail hub to the outside world, so the traffic is finite, and does not impact the surrounding road network. Also... since there's no direct rail connection between the internal lines and external lines, the external lines never get overloaded... in Rockwood V1, big spikes in Cargo trains crippled the passenger lines bringing tourists into the city,
So far it works well, even with a queue of trains waiting to unload everything keeps moving reasonably well, and there's no impact on the road network. I use the Biogas Silo extensively for trash collection, so there's one of those within the closed loop, but wince natural disasters DLC comes with Helicopter Police, Firefighters and Air Ambulances, the services are all taken care of. I didn't even have to put anything in for workers to access the site.. though I will put in a bus only route at some stage.
It is nice to see that the transport links up, and they use it. 
Not rushing it, add a bit more bits and pieces when I am in the mood after seeing things are stable. I have all the progs I need now for work. Didn't think I had any work until about Sept because of the situation until last week, so wanted to get the basics sorted as quickly and as easy as possible. 
Not really interested into tracking down what went wrong as I have a long list of Mods and I don't want to be searching through does and doesn't work with what if I don't need to. 
