Sixty-Seven Millimetres
Two railways terminate in Dar es Salaam a few kilometres apart and cannot exchange a single wagon, because their rails are sixty-seven millimetres out. That gap is the clearest surviving evidence of what the TAZARA line was built to do, which was never primarily to serve Tanzania.
Trains leave Dar es Salaam on two railways that have nothing to do with each other. The central line, laid by the Germans between 1905 and 1914 and running 1,254 kilometres to Kigoma on Lake Tanganyika, is metre gauge: its rails sit 1,000 millimetres apart. The TAZARA line, which starts at a terminus out on Nyerere Road and runs 1,860 kilometres south-west into Zambia, is Cape gauge: 1,067 millimetres. Sixty-seven millimetres, about the width of three fingers, and no wagon built for one will run on the other.
This is not an accident and it is not incompetence. It is the single most legible fact about why the second railway exists, and once you see it the whole project reads differently. TAZARA was not built to move Tanzanian goods. It was built to move Zambian copper, and it was built to the gauge Zambia already had.
The problem was a border, not a distance
Zambia became independent in October 1964 with its economy resting almost entirely on copper and no coastline to export it from. Every viable route out ran through a government it was about to fall out with. The southern line went through Rhodesia, whose white minority government declared unilateral independence in November 1965. The western route was the Benguela railway through Portuguese Angola. South of everything was South Africa. Kenneth Kaunda had committed Zambia to the liberation movements in all three, and had then to ship his copper through them.
Kaunda and Julius Nyerere wanted a railway to a friendly port at Dar es Salaam. They asked Britain, the United States, the United Nations and the World Bank, and were turned down by all of them; a World Bank study in the early 1960s judged the line uneconomic, which by the arithmetic of the day it was. The stopgap was the Great North Road, tarred with Western money and worked by Zambian and Tanzanian lorry drivers hauling copper north and fuel south over a route everyone involved called the Hell Run. Then China said yes. An agreement was signed in Beijing in September 1967, and the finance was an interest-free loan of roughly 400 million US dollars, repayable over thirty years from 1983 — at the time the largest single foreign aid project China had ever undertaken.
Two African governments that could not buy a railway on the open market went and found a lender who was buying something else. Everyone in the room knew what the other party was getting.
Building it
Construction ran from 1970 to 1976. At the peak there were something like sixteen thousand Chinese workers on the ground at once, alongside tens of thousands of Tanzanians and Zambians, and the finished line carries around 320 bridges, 22 tunnels and 93 stations. The hard part is the 157 kilometres between Mlimba and Makambako, where eighteen of those tunnels carry the track from around 300 metres on the Kilombero floodplain to over 1,800 at Makambako. A cemetery on the edge of Dar es Salaam holds the graves of the Chinese workers who died doing it. Freight started moving in 1975 and the line was formally handed over to the two governments in July 1976.
What the gauge locked in
Choosing Cape gauge was the correct engineering decision for the stated purpose. Zambia Railways ran on 1,067 millimetres, as did the whole southern African network it was designed to make redundant, so a copper wagon loaded on the Copperbelt could run to the Indian Ocean without being unloaded once. The cost of that was paid at the other end. In Dar es Salaam, freight arriving on TAZARA cannot be transferred onto the metre-gauge central line and sent inland; it has to be craned, trucked or shipped. Tanzania financed no part of the construction but hosts 975 of the 1,860 kilometres, and got a railway that could not talk to the one it already had.
Below capacity, for a long time
TAZARA was designed to shift on the order of five million tonnes a year. It has spent most of the last two decades moving a small fraction of that, and Zambian copper largely goes out by road again — south to Durban, or north over the Tanzanian highway that runs parallel to the tracks. The reasons are cumulative rather than dramatic: locomotives out of service and not replaced, deferred track maintenance, a joint Tanzanian-Zambian authority with two governments and one thin budget, and washouts in the rainy season that took months to clear. Passenger services never stopped, which is why you can still buy a sleeper, but they run twice a week and arrive when they arrive.
The third gauge
In September 2024, at the China–Africa summit in Beijing, Tanzania and Zambia signed a memorandum with China Civil Engineering Construction Corporation for a thirty-year concession to rehabilitate and operate the line, reported at around 1.4 billion US dollars. That company is the direct descendant of the builder: CCECC was spun out of the Chinese Ministry of Railways' foreign-aid department in 1979, and it was that department which laid the line in the first place. Meanwhile Tanzania has been laying a railway of its own on the alignment it actually wants — the standard-gauge line inland from Dar es Salaam through Morogoro to Dodoma, electrified, built by a Turkish contractor and paid for substantially out of Tanzania's own budget, carrying passengers since 2024 and eventually intended to reach Mwanza on Lake Victoria. It is 1,435 millimetres wide. That makes three gauges in one country, none of which can lend a wagon to either of the others, and it is the clearest statement Tanzania has made about the difference between a railway you are given and a railway you choose.