Rebuilding a vital rail in Mozambique. Restored Limpopo link could help free black neighbors from dependence on South Africa

As soldiers armed with rocket launchers and assault rifles fan out into the thick woodlands, crews of Zimbabwean railroad workers rock to and fro, straightening newly laid track with huge crowbars. The troops, combined units of the Mozambican and Zimbabwean Armies, protect the work gangs from attacks by guerrillas of the Mozambique National Resistance Movement (Renamo) who have vowed to halt the rehabilitation of the country's southern railroad, known as the Limpopo.

The 350-mile long railway, which links Zimbabwe to the huge port at Maputo, Mozambique's capital, is the latest regional transport artery being rebuilt by a combination of international finance and local initiative.

When completed, the Limpopo could handle 3 million tons per year, permitting Zimbabwe to shift virtually all its foreign trade from South African transport routes to Mozambican ports. It could also serve Botswana, Zambia, and even Zaire.

The nations of Southern Africa are taking steps to free themselves from dependence on South Africa's transport services for several reasons: moving goods through South Africa increases the transport costs and the distances goods have to travel; they fear transport services could be cut off if the political conflict in South Africa worsens or if South Africa retaliates against them in response to international sanctions against it.

``Once the work is finished, we will be effectively independent of South Africa,'' said one Zimbabwean official. ``The transport lock they have on us will be broken.''

The National Railways of Zimbabwe (NRZ) has already rebuilt about 70 miles of the track, replacing rotten wood sleepers with concrete ones and repacking them with new granite ballast. NRZ crews are currently 20 miles east of this small railroad town and advancing 10 miles per month toward Maputo, which lies about 280 miles south.

Neglected and sabotaged for a decade, the rail link to Zimbabwe running along the Limpopo River has been out of operation for the past five years. But buoyed by new pledges of $80 million from Britain, Canada, the United States, and other Western donors, and security commitments culled from Zimbabwe's 45,000-strong Army, railway officials are confident the program is unstoppable, despite the rebel threat.

The Zimbabwe Army successfully protected a similar rehabilitation program for the 196-mile Beira Corridor in central Mozambique, Renamo's heartland. Although the port is still being refurbished, the track itself is fully operational but attacked almost daily by Renamo rebels.

The port at Maputo is especially important because, unlike Beira, it is a deep sea port and its channel is not silted up. Beira requires constant dredging. Maputo is also ideal because it has special handling facilities for key Zimbabwean exports such as steel, asbestos, and citrus.

As NRZ pushes on, it hauls in tankers of water and diesel for power generators, bringing life to the desolate villages along the line. Women in Mapai say they no longer have to walk eight miles for water.

By late November, Mozambican and Zimbabwean officials hope that up to three trains a week, carrying goods from Botswana, Zambia, and Zimbabwe will be making the run from the border town of Chicualacuala to Maputo.

NRZ still has 230 miles to go - Zimbabwean soldiers will clear the way ahead - to finish its section of the rehabilitation. The Mozambique railways is just beginning work on the 50 miles from Maputo to the town of Manhica that it plans to rebuild. So until 1990, there is little chance that much traffic will move on the line.

In the meantime, Maputo port itself is getting a major facelift, with aid from Western nations, British port managers, and, ironically, a South African engineering firm. Relations between South Africa and Mozambique have long been strained. Mozambique accuses South Africa of trying to sabotage its transport routes, through the rebels, who Pretoria is generally believed to back.

Also, in post-independence years, South Africa imposed sanctions on Maputo, drastically reducing traffic through Maputo port.

Now South African exporters of coal and citrus in nearby Transvaal Province want to use the port and Pretoria has loaned Mozambique $3 million to fund work on port facilities.

Despite the progress on the Limpopo line, some analysts remain skeptical that Mozambican and Zimbabwean security forces, with modest non-lethal military aid and training from Britain, can protect the Limpopo from Renamo saboteurs.

Just 50 miles west of the line is South Africa's Kruger National Park. It is believed that a rebel logistics artery runs through this park to the operations room of South Africa's five reconnaissance regiments at Phalaborwa in Transvaal Province.

And 30 miles east of here lies a major rebel base outside the railroad town of Combomune.

``The problem is not keeping the line open, because if Renamo blows up the track, we can have it operational again in a day,'' said a Maputo port official. ``But if they do it often enough, the line will not be commercially viable.''