Hatch to polyline
AutoCAD has the capability to generate the boundary of a Hatch object [select it and right-click], to draw the outline of it as a Polyline or Spline. But what you're asking seems pretty impossible to automate. There are too many how-in-the-world conditions. Like this:
The highlighted Hatch pattern contains parts that would not only need to become separate Polylines, but with different widths. And the near-vertical parts really ought to turn into a Polyline that would incorporate parts converted from multiple other Hatch patterns. And the near-horizontal part doesn't relate in the same way to what it meets at the left end as to what it meets at the right end.
Similarly, here's another situation where too many Polylines would need to result from one Hatch, most of which should be parts of Polylines coming from other Hatches, and their ends are not even squared off as those of Polylines with width must be, and the "ring" part can't be like what the DONUT command would make because of the cut-in of its width:
And what would expect [even if converted manually] for the radiused-connection ends, and the circular parts, etc.?
Here's an especially impossible situation [each color is a different Hatch object]:
And there are places with as many as three Hatches on top of each other. [Maybe more in some places -- I didn't check through all of it.] The one that's yellow above overlays part of two red ones, except for its funny little tail in the circle next to the green.
I don't like to sound discouraging, but it looks like something that could not be automated into a routine that would be able to figure out what to do with which parts of which objects. You are probably stuck with the manual approach -- generate the boundaries, break the results into pieces relevant to individual roadways, do some Offsetting of half the widths to make center-line routes, Extend and Trim and Join to get the right overall routes for each roadway, and give them appropriate widths. [And figure out what you want for the radiused corners and circles.]
