The freight train rumbles over the Blue Nile bridge and snakes through the capital. It could take weeks to reach its destination, in Darfur, for despite the potential to link up a divided nation, Sudan's railways are derelict, after years of sanctions and neglect.
With more than 5,000 kilometres (3,100 miles) of track, Sudan has one of the longest railways in Africa, extending from Port Sudan on the Red Sea to Nyala in the war-torn west, and from Wadi Halfa on the Egyptian border to Wau in the far south.
But it now carries less than six percent of Sudanese traffic, and the last passenger train to depart from north Khartoum station left six months ago, according to a policeman guarding the empty building.
Prior to that they ran twice a week, he said, leaving early in the morning and arriving at the northern border town the following evening, covering a distance of around 900 kilometres.
"There are passenger trains still running. But they are very rare," admitted Mohammed Ahmed Makkawi, the general manager of Sudan Railways Corporation.
Like other officials in the sector, Makkawi blames the poor state of Sudan's narrow-gauge train system on US economic sanctions, first imposed in 1997 and renewed as recently as November.
"Most of our locomotives are from America, but most of them are out of service because of sanctions. We can't get spare parts," he told AFP. However, Khartoum has managed to buy new locomotives from China in recent years.
"We are trying to get financing for another track, to make it a standard gauge, so that it can carry a lot of equipment and goods and passengers, and be much more reliable," he added. "The existing tracks are very old," Makkawi said.
Most of the tracks are indeed ancient -- a staggering 73 percent of the railway lines were constructed before 1930 -- with the 50-kilometre branch line connecting Muglad to the Abu Jabra oil field being one of just a few to be built in the last half century.
Yet plans to build a new line from Port Sudan to Khartoum, the busiest route, would cost an estimated $1 billion (or 705 billion euros), money that the destitute Sudanese government simply does not have.
We are trying to get financing for another track, to make it a standard gauge, so that it can carry a lot of equipment and goods and passengers, and be much more reliable
Mohammed Ahmed Makkawi
Establishment of rail
Khartoum is connected to Aweil, a town in the soon to be independent south, with trains carrying thousands of southerners there prior to January's landmark referendum on independence for the region.
But the line down to Wau, which was used by the Sudanese government in its 22-year war against the southern rebels, was out of action for many years after the bridge in Aweil was destroyed, although railways officials say it was fixed in 2010.
Ironically, it was conflict that initially prompted the development of Sudan's railway.
The first section of the present-day network was built by the British in the late nineteenth century to support their military operations against Sudanese leader Muhammad Ahmad al-Mahdi, who had defeated the colonial forces some ten years earlier.
It was later expanded, and used profitably to export animals, sugar and cotton primarily from Gezira state, Sudan's agricultural heartland south of Khartoum, between the Blue and White Nile.
But despite a string of belated reforms in 2005, the Gezira farming scheme has experienced gradual stagnation, and the railway system declined partly as a result.
Not sanctions, but union activists
Sudan's railways prospered in the 1960s and 1970s, driven by a thriving agricultural sector and foreign investment, and their decline mirrors the wider stagnation of the Sudanese economy.
Ahmad Sikainga, professor of African social and economic history at Ohio State University, points to another key factor in its demise, namely the determination of successive governments to suppress the rail workers union, which formed the core of Sudan's once-powerful labour movement.
"The railway continued to prosper until the early 1980s, and its decline was the result of a combination of economic and political factors," he told AFP.
"The current government bears a big responsibility as it dismantled whatever was left. In 1992, it dismissed thousands of railway workers and trade union activists."
Rail workers now receive paltry salaries, the SRC suffers from chronic administrative problems, the trains and tracks require extensive maintenance and passengers report frequent stoppages.
Abdel Fadeel al-Nur had a particularly bad experience last year. The 28-year-old engineer got a job with the rural development fund in Nyala, South Darfur, and had to get five tractors there from Khartoum, so he decided to put them on the train, having done the 900-kilometre journey some years earlier in just three days.
"I left Khartoum on May 13 and arrived in Nyala on June 13," said Nur.
"We stopped for one day in Sennar, because of technical problems, and then again in Kosti for three days. Then we stopped for 12 days in Rahad, for more technical repairs to the train. We were also delayed because of fighting in Darfur," he added.
"I don't think I will ever travel again by train."
The current government bears a big responsibility as it dismantled whatever was left. In 1992, it dismissed thousands of railway workers and trade union activists