I have seen many other state maps, and they call unimproved roads "jeep trails"
No idea how NJDEP does things, but I've been working on a large regional map based on USGS road data. The current data is based on
TIGER shapefiles from the US Census Bureau. This was originally very crude data, only intended to help census-takers find houses. So, if there was a little winding dirt road, they might have represented it with a straight line since all they cared about was how many houses were on it. But in recent years, the quality of this data has improved a lot - to the point I decided to use it instead of OpenStreetMap which has (IMO) become kind of a crowd-sourced mess.
Anyway, the "Jeep Trails" are also called "4WD Trails" sometimes. There aren't a whole lot of roads with this designation in the Pines, there are more in some other states. This is how they are
officially defined.
Although the quality of the paved roads in their database has improved a lot, there really are very few unpaved roads in it. This is further complicated by their definition of minor roads which makes no distinction between paved and unpaved.
I have resorted to hand-tracing unpaved roads from the legacy 24k maps because the USGS database just doesn't include them. You can see this by comparing the USGS digital topo with the legacy topo - here's a
random example in the Pines.
Tracing roads is a very time-consuming task, which is why it's taking so long for me to finish this new map. One interesting thing that I noticed in some places - like the Adirondacks - the unpaved roads aren't part of the USGS database, however most of them are still there but now classified as trails with new names.
Not trying to make any sort of point related to the MAP here... just offering a bit of insight into the road classification system.