As China’s ambitions in Africa have expanded in the past few years, a number of analysts have taken to assessing the continent with pins in the map, much as colonial cartographers did more than a century ago.

This time, however, the pins do not represent putative borders. Rather they reflect the progress of grandiose Chinese-backed infrastructure projects, in particular railways and roads, that promise to open up the continent.

For African governments, the investment in infrastructure is arguably the most important spin-off of the intensifying liaison. For years business in Africa has been hampered by poor transport links between countries and regions.

Adding to the allure of the Chinese contractors, they have completed many of their contracts with dizzying speed. Song Jing, an engineer for China National Electronics Import and Export Corporation, a state company, who has worked on a number of prestige projects in Angola, was speaking for Chinese colleagues across Africa when he proudly told the FT earlier this year: “No one can finish work as quickly as we can.” Khartoum might be tempted to agree with such a claim after a Chinese state company completed a pipeline from the oilfields to Port Sudan in two years. This was in marked contrast to the progress of most western-backed infrastructure projects in Africa in recent decades, which have frequently taken years even to get started.

In recent months in several countries the “pins” have all but stopped moving across the map as Chinese construction companies have encountered some of the difficulties that have long bedevilled large projects in Africa, in particular that of cost.

In Angola, western diplomats believe progress has ground to a halt on the reconstruction of three railway lines, including the legendary Benguela Railway which in colonial times linked the port of Lobito to mineral-rich areas in what is now the Democratic Republic of Congo and Zambia.

The government had tipped these three projects – the other two are intended to link Luanda, the Angolan capital, and the southern port of Namibe to the interior – to be completed by the end of last year. Now, however, analysts say no one can predict when they will be finished.

Diplomats and aid workers believe the delay may be linked to funding difficulties faced by one of the big participants in the rail projects, the China International Fund, the Hong-Kong construction arm of Beiya International Development, which imports oil from Angola to China.

It secured a range of construction projects in Angola linked to a government programme to rebuild infrastructure devastated in the civil war that ended nearly six years ago. But late last year the Angolan government downgraded by two-thirds its estimates of the line of credit the CIF was thought to have provided.

Other big projects in Angola have also fallen behind schedule, including a planned airport outside Luanda. “Plans have been given to civil aviation authorities to review,” says one western diplomat. “But we are not even sure the contract has been awarded.”

In possibly the most striking case of a stymied grand project, the Angolan government early last year cancelled plans for an oil refinery to be built by the Chinese outside Lobito.

Similar stories of snags can be heard across the continent. In Nigeria, plans for a number of Chinese-backed infrastructure projects linked have not yet come to fruition. And yet the scale of Chinese ambitions does not appear to be dented. A memorandum of understanding has been signed between the Congolese government and a Chinese consortium, which outlines a vast project of three motorways, a railway, 32 hospitals and two universities.

Martyn Davies, director of the Centre for Chinese Studies, recalls officials from the Shanghai Construction Group telling him that its most profitable projects are in Africa. Chinese construction companies are to get the contracts for the infrastructure around the five planned special economic zones in Africa.

“The Chinese government will create the enabling environment into which Chinese companies can follow,” he says.

In Gabon plans are under way for a Chinese state company to build a railway linking the giant Belinga iron ore project to the coast 500km away. “BHP Billiton hummed and hawed about the project and decided it wasn’t viable because of the costs,” says Michael Power, an analyst at Investec Asset Management. “It’s a wonderful example of what