Private equity aboardA LONG line of smoke-belching lorries clogs the highway for miles outside Mombasa, Kenya’s main port. They are waiting to collect shipping containers that they will haul across 1,200 grinding kilometres to Kampala, Uganda’s capital. Doing so is slow and costly. Yet for a quarter of a century this was the only viable way of shipping goods into east Africa’s interior. The moribund railway was even slower, and thoroughly unreliable: at best it would take 12 days to move a container by train.Today a procession of brightly painted locomotives (pictured) belonging to Rift Valley Railways are taking an...