Not tried this, just thinking off the top of my head. How about using the point density tool in Arcmap, to create a raster, then threshold that, for example you decide a density of 10 points or greater is a road, everything else becomes no data. Then use the raster to polyline tool. Not sure how this would work when comparing highways with single tracks? You will probably want to use the Thin tool before the final conversion to a polyline dataset. The Thin tool tends to create spurs which need editing out and gaps closed. So a lot of work...
Changing the cell size of your density raster will influence what gets generated.