Deep in Kenya's Great Rift Valley, members of the National Youth Service tirelessly swing machetes to clear dense shrubs obscuring railway tracks more than a century old.

It's a distinctly low-tech phase for China's Belt and Road drive in Africa to create the trade highways of the future.

There's not enough money left to complete the new 1,000-km superfast railway link from the port of Mombasa to Uganda. It ends abruptly in the countryside, 468 km short of the border, and now Kenya is resorting to finishing the route by revamping the 19th-century colonial British-built tracks that once passed that way.