The first leg of the 35-mile journey from Ghana’s capital city, Accra, to the Fairafric chocolate factory in Amanase on the N6 highway is a quick ride. But after about 30 minutes, the smoothly paved road devolves into a dirt expanse without lanes. Lumbering trucks, packed commuter minivans, cars and motorcycles crawl along craggy, rutted stretches bordered by concrete dividers, muddy patches and heaps of rock.