Having taken the train from Nairobi to Mombasa, I am sure it already exists ....

But a modern modern Chinese owned railroad duplicating the existing one, means they can control it. Maybe has some abilities the old line can not handle.

I also know the shortcuts Chinese infrastructure projcts take in the third world, having seen Chinese built highways in Sri Lanka. Hated by th locals, it cuts across rivers, mountains, hillsides etc without any environmental concerns, or worry about future landslides. Western companies would not get away with the crap the Chinese build on the cheap ...