Query: What are S roads, the mid-level that connects district capitals to regional capitals?
Context: During the wet seasons these roads typically become impassable. The next higher level road is a secondary road and typically is a single-layered asphalt road that connects district capitals together and those to the regional capitals. Roads that are considered primary roads are those that are fully asphalted (throughout their entire length) and in general they carry traffic between all the major towns in Eritrea.