If 2 years in the roads have no grass or weeds, the soil is too compacted for anytype of growth. I saw the same thing on my logging decks and roads in SE NC. I pulled an atv drag over them everytime I went to the farm to try and tear up as much ground as I could, especially when its wet. Now, they have some grasses growing which will speed up the process. You may want to focus on clearing some micro plots in the jungle and use the roads for access and shooting lanes. Feather the edges and clear some trails to help nudge them where you want them to go.