Was this true? Chinese companies are building new railways in Kenya and Nigeria: should people in these countries be wary?
Not if we can believe Wikipedia. The on-line encyclopedia states that Tazara was not built to a Chinese railway gauge. China uses mainly standard gauge (1435 mm). Tazara was built using the Cape gauge (3 ft 6 inches) common across the former British colonies in Southern Africa. Zambia used Cape gauge in its railway system, but German-built lines in colonial Tanzania used a different gauge: 1000 mm (3 ft 3 3/8 inches).
That's why the railways don't link up. It's a problem constructed by competing colonial powers a century ago.
The railway currently being built by a Chinese company across Kenya is using standard gauge, but this wasn't a Chinese decision imposed on Kenya. (For more on Kenya's railway gauge debates, see this link.)