When I went to Maker Faire Africa, I wanted to better understand the Abidjan-Lagos corridor (part of the Trans–West African Coastal Highway which I had previously studied as part of the Tema research. Here are shots from the road via Togo and Benin. Having never before seen in-between Lome and Lagos, the scenic route was well worth it. Especially when set to Francophone radio soundtrack (try Africa No. 1 Lomé, Togo).
And here is World Bank perspective on ECOWAS highway infrastructure (2011):
Traffic along the key regional corridors is moderate to heavy in both cases; with the most heavily used routes typically those in poorest condition. The regional corridors almost always carry at least 300 vehicles per day along most of their length, and more than 1,000 vehicles per day on at least 20 percent of their length (table 2.2, figure 2.1b, figure 2.2b). Overall, the most heavily used corridors are the two gateways into Burkina Faso, and the Cotonou-to-Niamey route. Ironically, these are also some of the corridors in the worst physical condition. The Dakar-to-Bamako route is one of the most lightly used, perhaps reflecting the existence of a parallel rail corridor; although the Abidjan-to-Ouagadougou route is used intensively, despite the existence of the rail alternative. Otherwise, the portions of the corridors falling in the coastal countries tend to be the most heavily used, almost always attracting in excess of 1,000 vehicles per day. Nevertheless, in absolute terms, such traffic levels can be considered no more than moderate. After all, 300 vehicles per day is the minimum traffic threshold required for paving to be economically viable. And none of the corridors exceed the threshold of 10,000 vehicles per day needed for toll road concessions to be economically viable.
The cost of moving goods along each of these key arteries is a key constituent of competitiveness for both international and intraregional trade. These costs break down into three components: the travel costs of moving goods, determined by road and rail freight tariffs; the administrative costs of moving goods across borders and through ports, determined by associated service charges; and the costs of time delays incurred by waiting at roadblocks, border crossings, and ports. The competitiveness of the different corridors can be gauged by aggregating transport, administrative, and waiting costs incurred along the route.