The Trans-Sahelian Highway or TAH 5 is a transnational highway project to pave, improve and ease border formalities on a highway route through the southern fringes of the Sahel region in West Africa between Dakar, Senegal in the west and Ndjamena, Chad, in the east. Alternative names for the highway are the Dakar-Ndjamena Highway or Ndjamena-Dakar Highway and it is Trans-African Highway 5 in the Trans-African Highway network. The highway passes through seven countries and five national capitals, and links regions of similar climate and environment which have cultural and trade links going back centuries. It is one of two east–west transnational links in West Africa and runs inland from and, for most of its length, roughly parallel to the Trans–West African Coastal Highway with a separation of about . Route and status Overall features, length and condition The Trans-Sahelian Highway has a length of about running through Senegal, Mali, Burkina Faso, Niger, Nigeria, and the far northern tip of Cameroon, ending at N'Djamena just inside the western border of Chad. All but about , mostly in western Mali, has been paved, but extensive sections elsewhere require rehabilitation or are currently under reconstruction. Most of the route uses existing national highways, but an optional route requires construction of a completely new road between Senegal and Mali. Detail of sections The cities and countries served, and status of the road are as follows (going east): In Senegal, Dakar to Tambacounda, , paved, in poor condition; this road has been paved for several decades. Linking Senegal and Mali between Tambacounda and Bamako, two options were proposed in the 2005 consultants' report a shorter more direct southern route via Saraya and Kita, about , using about of road paved in the 1990s of which most was in good condition, and requiring construction of of new road and the paving of of earth road; a longer northern route of about via Kayes, Diéma and Didjeni, utilising national roads of Mali which are paved. In south-eastern Mail, Bamako to Sikasso via Bougouni, , paved before 1990 and in fair condition. Sikasso to Koloko at the Burkina Faso border, paved and in fair condition. Burkina Faso section: via Bobo-Dioulasso, Ouagadougou, Koupéla, and Fada Ngourma, paved and in good condition except for paved section before the Niger border, due to be rehabilitated in 2003–5; Niger section: of which was in poor condition, via Niamey, Dosso, Dogondoutchi, Birnin-Konni