There’s probably a gap due to the edge crossing a tiny part of a triangle. Examine the edges of the road closely to find it. If I had the file I would give Eneroth’s Weld tool a run over the geometry. After it has run I would select the welded edges and see where they stop. Those would be places to look for gaps. If it really is due to some tiny triangle being formed, you could use the Dave Method to get around that or edit the terrain a little to eliminate the small triangle.