The jam has seen thousands of vehicles backed up along a 60-mile-long stretch of road between Inner Mongolia and Beijing. Motorists have reported travel times of up to five days to get through the king-sized snarl.
The immediate cause of the jam is road construction on National Expressway 110 (G110). But those repairs were needed due to damage from a recent surge in jumbo truck traffic carrying coal and some agricultural products, the Global Times reported.
There is another route from northwest China to Beijing, but it's open only to trucks 4 tons or lighter and charges costly tolls that transporters prefer to dodge, the Times reported.
"We are advised to take detours, but I would rather stay here since I will travel more distance and increase my costs," a coal truck driver surnamed Wang told the Global Times. "The number of roads from northwest China to Beijing are limited. ... Why should I pay the toll fee?"
China depends on coal for 70 percent of its energy needs, and that appetite shows no sign of slacking amid the nation's breakneck economic growth.
After authorities closed thousands of dangerous coal mines in Shanxi Province, Inner Mongolia has become China's largest source of coal, Bloomberg reported, providing 21 percent of output compared with Shanxi's 18 percent in 2009.
That coal is transported mostly by truck because of a lack of rail capacity, the news agency said, and it quoted an expert who expected the situation to improve in "three or four years" after new rail lines are completed.
For now, much of Inner Mongolia's coal is moved by truck in the Beijing area to ports such as Tianjin, and from there is shipped to power plants in southern China, Bloomberg said.
The Christian Science Monitor reported that many of the trucks crawling through gridlock are carrying coal illegally mined in Inner Mongolia. Drivers are taking the G110 route because it's free of coal checkpoints that would require bribing inspectors to ignore the illegal loads, the Monitor said, citing a report in the Beijing News.
The Global Times said the jam was hardly new: a similar tangle in June lasted nearly the entire month. It reports that construction is due to last through Sept. 13 -- meaning potentially weeks more of traffic pain.
China's traffic woes go beyond coal trucks, though. A study by IBM released in June rated Beijing and Mexico City the world's worst cities on its "Commuter Pain Index," with a 99 out of 100 rating compared to Los Angeles' 25.
The 20-city survey found that 69 percent of Beijing respondents had canceled or changed their travel plans due to bad traffic in the last three years, the highest rate of any city polled. That's despite having one of the world's highest bus-use rates, at 44 percent.
Beijing has 4.2 million cars on the road, a number expected to increase to 5 million by the end of the year, according to the Global Times, and 7 million by 2015, according to a transport official quoted by the Xinhua state news agency.
That official said average driving speeds in Beijing would slow to below 9 mph by 2015 from 15 mph now if trends continue.