We were going to implement a spline system, like the path editor, where at each nodes, it spawns and orients an object.
Would be great for railings, telegraph poles, hedge rows, field borders, crop rows, fences etc..
This tool would not be part of the road system though, and could be used to just generate a scene faster.
As for the road, i think the material & texturing would be the hard part, grabbing some vertices and extruding won't be too much work. Won't enjoy generating the tangents and normals though bleh
It could be done as a little 2d window that appears and you move the vertices around for a profile. At the moment, the road is created from a spline, so in a sense it already does this. It generates vertices to the left / right of the centre line, together with the correct orientation to form a road.
But again, putting a texture/material onto the face would be tough. Especially for something like a railroad (wood beams, metal lines, gravel ground).