How to prepare road network for routing in QGIS or GRASS

Question

I have been working on a road network and I want to run shortest path algorithms on it. One problem is that some lines come very close to each other, but are not connected.

Is there a way to connect these lines when they are closer to each other than some threshold?

Thanks

Answer 1

Manual snapping, connect to operations. create junction at pseudo intersection or over/underlap. likely a case by case scenerio to see if disconnect is valid, and then manulay digitize or snap.