Road classification in Kenya takes into account the function the road serves i.e.

1. If the Road serves as a link between centres of international importance, crossing international boundaries or terminating at international ports (Class A roads-International Trunk Roads)
2. If the road links nationally important centres, principal towns or urban centres (Class B roads-National Trunk Roads)
3. A road that links provincially important centres to each other or to higher class roads are Class C roads or Primary Roads
4. If a road links locally important centres to each other or to a more important centre, or to a higher class road it is a class D Road (Secondary Road)
5. Any road link to a minor centre, market or local center is a Class E Road(Minor Road)

In addition there are other Classes of road as per usage (Special Roads) i.e;

1. Forest Roads Class F Roads
2. Roads serving Schools, Hospitals and Government Institutions Class G roads
3. Roads leading to Coffee(Kahawa) growing areas Class K Roads
4. Roads accessing settlement schemes Class L Roads
5. National Park Roads Class P Roads
6. Roads Accessing Rural areas Class R
7. Roads Accessing Sugar growing areas Class S
8. Roads accessing tea growing places Class T Roads
9. Unclassified Rural Roads including those leading to areas with mineral deposits Class U Roads
10. Roads Accessing Wheat growing areas Class W Roads