Drag Transit Gates

Although it is completely possible to 'free fly' a ship faster-than-light, it comes at a cost: the more massive the vessel, the more fuel is needed to generate sufficient power. For anything outside of gigantic combat ships, it's preferable to send large freight and passenger craft on 'rails', using drag transit gates. 
Terminals are lined up along specific routes, corridors between systems that are free of major obstacles. Vast streams of exotic dark matter are jetted between the terminals thanks to the substance's interaction with normal space: a vessel entering a gate is thus "dragged" between terminals, at FTL speeds, without requiring them to hold and burn huge amounts of fuel.
Huge hubs act as switching stations, allowing vessels to move from one rail to another. Smaller vessels and cargo hubs offload passengers and freight, and shuttle them to smaller worlds and stations that do not lie directly along the path of a gate.



DTG Figures