Do any motorways exist in Bahrain?
A trunk road is a major road with 3 or more lanes and a central reservation. Furthermore, entry/exit is primarily by slip roads rather than traffic-light controlled junctions.
A major road, usually with 3 or more lanes and a central reservation, but with traffic-light controlled junctions.
A secondary road is metalled and usually has pavements (sidewalks) and lamp-posts. It may be single or dual-carriageway.
A minor road, which is usually single-carriageway. It is metalled but may not have built-up pavements or kerbs.
A minor road, usually single carriageway. The difference between an unclassified and a tertiary road is that an unclassified road serves only itself and other unclassified roads connected to it, whereas a tertiary road tends to actually 'go somewhere' (another part of town, another town or so on).
A road which would otherwise be unclassified, but which is primarily lined with housing. NB a tertiary road with houses along it is still classed as a tertiary road.
A road whose only purpose is to serve an individual building, or to serve a set of buildings set back from a major road. Note that some services roads to large conference centres and similar can be multi-lane with a central reservation. But they are classed as service roads because of their purpose.