If there will be no actual "street running" on this section of track, I suggest that you buy some Atlas O 2-rail track that has a correct solid flat-topped cross-section (rather than hollow tubular track) with correct 1/48 (0.148 inches) scale rail height. You can put wood planks between the rails while leaving openings for wheel flanges adjacent to the insides of the rails. You can purchase planking for between the rails from Blair Line... As mentioned before, the height of planking or asphalt pavement should be just below the top of the rails. I have cobblestone streets on my layout (bought from Monster Models) but I don't think they're in business now.
MELGAR