A hundred-kilometre traffic jam lasted twelve days in 2010

A hundred kilometres of stationary lorries for twelve days running: that is what happened in August 2010 on China National Highway 110, north-west of Beijing. The queue began to form on the 14th and was not cleared until the 26th. It is the longest traffic jam ever documented.

It was not an accident either. A jack-knifed truck, a rollover or a flash flood produce delays of hours. To produce twelve days you need the road's own arithmetic to stop adding up, and the 110's had not added up for years.

It is worth placing it on the map, because the scale is deceptive. Highway 110 is one of China's great roads: it joins Beijing to Yinchuan and runs 1,357 kilometres. The queue formed on the north-western stretch, between Jining, in Inner Mongolia, and Huai'an, already in Hebei, about a hundred and fifty kilometres from the capital. It was a freight queue in open country, on the road by which the coal of the north enters Beijing.

The 110 and the Beijing–Lhasa expressway, which run side by side along that stretch between Inner Mongolia and Hebei province, are the route by which that coal travels. Inner Mongolia pulled 602 million tonnes of coal out of the ground in 2009 and expected to reach 730 million in 2010. That extra coal had to travel somehow, and the region's railways could not take it: there were not enough tracks or trains to move what was being extracted. So it went onto lorries. Traffic on the road had been growing 40 per cent a year, and by the summer of 2010 it was carrying 60 per cent more vehicles than it had been designed to take.

That sentence is worth reading twice, because it is the heart of the matter. A road is not sized for the traffic a region's economy would like it to have, but for the traffic that fits along it. The 110 was laid out for the traffic of a farming and mining area, and ended up acting as a conveyor belt between the mines of a whole province and the country's capital. Nobody decided it should be that way: it is what was left when the mine grew faster than the railway.

A road at 160 per cent of its capacity is already a bad road. What turned it into a hundred-kilometre queue was what happened five days after the bottleneck began: the roadworks started. The surface had to be repaired, precisely because the coal lorries were destroying it, and the repair left the road with half its capacity. A road taking 60 per cent more traffic than it could absorb was left with half the room to absorb it in. And the works were not due to finish until mid-September.

From then on the queue could only grow. It is funnel arithmetic: if more comes in than goes out, the difference accumulates, and it accumulates every day until somebody changes one of the two figures.

On highway 208, which runs parallel, there was a coal inspection station where loads were weighed and paperwork checked. Drivers who were overloaded or whose documents were not in order took a detour to avoid it. And the detour was the 110, which was already at 160 per cent before it took them in.

What it was like inside the queue is told by the drivers themselves. Some advanced one kilometre in a whole day. Some spent five days in there, sleeping in the cab, getting out to stretch their legs along the verge and climbing back in without having lost their place, because there was no place to lose. People played cards and chess between the lorries, on the tarmac, with the engines off.

And an economy appeared. Villagers from the settlements alongside started coming up onto the road with bicycles loaded with food and drink and selling it to drivers who could not go and fetch it themselves. A bottle of water that cost one yuan went for fifteen. Instant noodles sold at more than triple their price. The drivers complained about it in the Chinese press and the sellers kept coming up, because the market was captive in the most literal sense of the word: a hundred kilometres of customers who could not go anywhere else.

Meanwhile, Chinese state television announced that the situation had "basically returned to normal". The journalists who were on the road reported otherwise: the queue was still there, the sellers were still coming up and the drivers were still sleeping in their cabs. That gap between the official statement and the hard shoulder is, in good part, why the 110 jam became famous around the world: it was not reported from an office, it was reported from inside.

The damage did not stop with the lorry drivers either. The Zhangjiakou area, in Hebei, lives partly off the weekend tourism that comes out of Beijing, and Zhangbei county went on to lose a third of its visitors compared with June. Nobody buys an excursion to a district whose only road is on the evening news.

The queue cleared on 26 August, and it cleared by changing one of the two figures in the funnel. The authorities let more lorries into Beijing, especially at night, when the city restricted heavy goods traffic; and they asked haulage companies to suspend shipments or find another route. Neither measure touched the road: they touched the flow going into it. And since the road stayed as it was, with the works running until September, the tailback formed again in September.

That is what explains why it was twelve days and not twelve hours. A queue fed by a funnel does not settle at some high number: as long as more comes in than goes out, it grows, and there is no point at which it fills up. What fills up is the space it has. The 110 is one thousand three hundred kilometres of space, so the queue had a hundred at its disposal and took them over at a rate of a little over eight kilometres a day, until somebody turned off the tap upstream.

And there remains the figure that best gives back the scale of it, and it is none of the big ones. There were drivers who advanced one kilometre in a full shift in the cab, starting and stopping, hand on the brake and eyes on the lorry in front. A person walking does five kilometres an hour. That same kilometre, on foot and in no hurry, takes twelve minutes.