Multiple causes aggravate monster traffic jam. Jiang Xueqing and Cao Li in Beijing and Cheng Yingqi in Zhangjiakou report.

Lu Yong looked through his windscreen toward the snake of unmoving traffic disappearing into the horizon and swore.

"I knew it," he said as he brought his truck to a stop.

It was the second time the driver had been caught in a giant traffic jam on the Beijing-Tibet Expressway in the past month.

"At least I'm not carrying fruit this time," said the 37-year-old, who was ferrying heavy machinery from Baotou in the Inner Mongolia autonomous region to Beijing.

Lu is just one of thousands of drivers caught up in the worst road congestion in recent decades, with many blaming a combination of high demand, limited capacity and ongoing construction work.

However, experts speaking to China Daily insisted the country's inadequate freight rail services have also exacerbated the problem.

Trains offer much larger volumes than heavy-duty trucks, yet most of the vehicles trapped in the congestion, which began with the first jam on Aug 14 and then a second on Aug 27, were carrying coal from Inner Mongolia to the capital.

Official data shows that less than 40 percent of the coal produced in Inner Mongolia is shipped by rail, which is largely due to a shortfall in capacity.

Railway services transported 2.1 billion tons of goods during the first seven months of 2010, a growth of 13 percent year-on-year. However, it is still not enough to meet demand, with China's total coal output alone reaching more than 3 billion tons last year.

"While the country has witnessed double-digit economic growth since the opening policy, its railways grew only about 1 percent between 1978 and 2004," said Liang Chenggu, a publicity official at the Ministry of Railways.

Although there are major plans to expand the nation's network, which already stretches to 86,000 kilometers, most of the work involves high-speed rail links, according to ministry figures.

"High-speed tracks can only be used for passenger services," explained Zhao Jian, a professor with Beijing Jiaotong University's school of economics and management. "The extra cargo capacity only comes when (existing) resources become redundant due to upgraded passenger services."

Some freight services are even halted for spring rush - the 40-day peak travel period during the Chinese New Year holidays - to allow for more passenger trains to run.

"(Resources such as) coal should be transported by rail rather than trucks but the capacity for cargo on the country's railways is just too low," added Guo Xiaobei, director of the National Development and Reform Commission (NDRC)'s institute of comprehensive transportation.

Supply routes

Coal and gas reserves are concentrated in western regions of China, like Shanxi province and Inner Mongolia, while consumption is largely in the east, thousands of kilometers away.

As few companies use rail freight services, the huge demand has put even more strain on a highway network that is struggling to cope with sheer weight of traffic.

Following the widespread closure of small coal mines in Shanxi in the last two years, more provinces in North China have turned to Inner Mongolia for their supplies. Companies in the region produced almost 602 million tons of coal in 2009 (slightly less than Shanxi's 615 million tons) and that figure is expected to rise to 730 million tons this year.

Growth in production means more traffic, however, and the number of heavy-duty trucks in the autonomous region is up 67 percent since last January, according to the Ministry of Public Security.

Hebei province, a major route for mines shipping supplies to eastern coastal areas, also saw an increase of 55 percent over the same period.

The number of vehicles on Inner Mongolia's roads was expected to hit 25,000 to 50,000 in 2033. Although no official figures were available, media reports suggest the region has already surpassed that prediction.

An average of 70,000 cars and trucks use the Beijing-Tibet Expressway between the region's capital Hohhot and its eastern border every day, three times the maximum capacity, said a toll station worker who did not want to be identified.

With winter and the peak time for coal sales approaching, road management authorities have some big challenges ahead, said traffic bureau official Zhang Minghai in Zhangjiakou, a city in Hebei.

To enter Beijing from the northwest, trucks weighing more than 4 tons must pass through the Jingxin Expressway (a section that overlaps the Beijing-Tibet Expressway) in Zhangjiakou, which later merges with Danla, Xuanda and Jingzhang expressways and National Highway 110.

Traffic jams have become a common problem and have caused huge economic losses.

"I could have driven between the two cities three times in the time I wasted stuck in the traffic jam," said trucker Lu Yong. "I could have earned around 900 yuan from each trip."

Authorities in Zhangbei county, one of the city's hottest destinations, have invested more than 2 billion yuan ($295 million) in its tourist industry, yet visitors numbers have fallen by a third since June, as travel agencies cancelled trips to avoid the congestion.

Zhangjiakou's farmers have also been affected as they largely provide vegetables for the capital.

Covering costs

With great demand for coal, transport companies are in fierce competition for business and, to save on costs, often overload their trucks, said Wang Dongming, a researcher at the NDRC's institute of comprehensive transportation.

Although the national standard fee recommended by the government is 0.5 yuan per ton per kilometer, freight firms often offer their services for just 0.3 yuan per ton per kilometer to win more contracts.

The cut-price rate means they need to ship more cargo using the shortest route.

Dong Shunsheng, a truck driver from Inner Mongolia who has been transporting coal for more than a year, said the Beijing-Tibet Expressway is the most convenient and cost-efficient route.

One alternative, National Highway 110, which is a two-way dual carriageway full of bumps where trucks stop constantly, has been under construction during the recent congestion problems. Another, National Highway 208, is an extra 200 kilometers and 33 percent more expensive, he said.

"Each extra kilometer adds at least 3 yuan to your costs, such as fuel and road tolls," said Jia Wensheng, 44, who drives a China Post van. "Drivers would rather waste time than money if they are not in a hurry."

National Highway 208 also passes through a coal quality supervision and inspection station in Datong, Shanxi province, where trucks are stopped and checked. As most are overloaded or do not have the right paperwork to carry coal, they avoid it and instead use the Beijing-Tibet Expressway.

"I pay 1,300 yuan for fuel, roughly 1,000 yuan in toll fees and about 600 yuan in other expenses," said Luo Jun, who transported coal from Hohhot to Shangyi county in Hebei. "If I carried only the 26 tons my truck is allowed to, the trip wouldn't even cover my costs."

Although companies argue overloading is unavoidable if they want to make a profit, experts say it is dangerous and seriously affects roads and traffic flow.

While the average speed on highways is 110 kilometers per hour, studies show that overloaded trucks can only travel at a maximum of 50 km/h, said researcher Wang.

To curb the rampant problem, Beijing police in August imposed restrictions on heavy-duty trucks using the city's expressways during the day. Other authorities have also set up checkpoints to catch offenders.

However, this involves truck drivers lining up to have cargo being unloaded and weighed, which some say contributes to the slow traffic.

The number of toll gates is also large, added Wang. Highways are managed by various provinces, which use the money collected to maintain the roads or building new ones.

Although he advocated for the reduction in tolls, Wang urged the government to create laws that ensure investment and maintenance of highways.

"At places where toll gates have been removed, the roads have really deteriorated," he added.

Lu Weidong, right, chief traffic police officer for Yanqing county in Beijing describes to his colleague, Xi Weizhen, how to ease traffic congestion in the transport control center on Aug 30. Li Shu / Xinhua

Heavy-duty trucks carrying coal supplies from mines in Shanxi province and Inner Mongolia autonomous region travel on the road to Beijing. Provided to China Daily

By Jiang Xueqing and Cao Li in Beijing and Cheng Yingqi in Zhangjiakou (China Daily)