Africa has spent years discussing the financing gap for mines. The more consequential capital is now appearing one layer below them, in the rail systems those mines cannot operate without.

The question has moved. It is no longer whether governments will let private operators onto state networks. Angola, Tanzania, Zambia, the DRC, Zimbabwe and South Africa have all answered that. The question is whether the rights those operators receive can carry debt.

The three corridors usually discussed together answer it very differently. In Angola, the concessionaire controls, maintains and upgrades the railway it earns from, under a thirty-year contract with obligations running in both directions. In Tanzania, the concessionaire rebuilds the line and hands it back. In South Africa, the operator supplies the trains and depends on track it cannot influence.

That third arrangement is the interesting one, because the draft agreement governing it is unusually candid. TRIM, the state body that now manages the network, is revising the document that sets access terms, and the version out for public comment grants access on an "as is" basis, with no warranty of the network's availability or condition and no claim available when it disappoints. Losses of the kind that actually arise, lost production, lost contracts, demurrage, are excluded. And either side can walk away on six months' notice, for any reason, with no compensation for the locomotives left behind.

The result is visible in the capital. Lobito Atlantic Railway raised US$753 million of development finance debt. Traxtion, South Africa's most committed private operator, raised US$86 million of equity. Both serve the same copper. The difference is what a financier could attach security to.