BEIJING (AP) — China's monster traffic jam has reared its head again, with trucks and cars backed up for up to 18 miles (30 kilometers) Saturday on a highway north of Beijing, although that is a third the size of what it was.

The traffic jam came four days after the break-up of an even bigger one — stretching to 60 miles (100 kilometers) at one point.

State media said the latest jam on the Beijing-Tibet highway was caused by an accident and road maintenance.

The worst of the jam started in Zhangjiakou, a city about 90 miles (150 kilometers) northwest of Beijing, and stretched into Inner Mongolia in northern China, with traffic creeping along in fits and starts.

A woman who answered the phone at the Beijing traffic management office said drivers should not take the highway. "The traffic flow is very slow," said the woman, who refused to give her name.

Traffic jams are part of daily life in China's major cities, with vehicles moving at a crawl in parts of Beijing for most of the day.

In the last traffic jam on the Beijing-Tibet highway, which started Aug. 14 and lasted about 10 days, state media said some drivers were stuck for five days with drivers on the worst-hit stretches passing the time sitting in the shade of their immobilized trucks, playing cards, sleeping on the asphalt or bargaining with price-gouging food vendors.

A bottle of water was selling for 10 yuan ($1.50), 10 times the normal price, Chinese media reports said.

The main reason traffic has increased on the partially four-lane highway is the opening of coal mines in the northwest, vital for the booming economy, which this month surpassed Japan's in size and is now second only to America's.

Officials eased the first jam by directing truckers to take a 180-mile-long (300-kilometer-long) detour, the China Daily said.

It quoted one truck driver, Lu Yong, who was stuck in both jams, as saying he should have prepared some food this time. "Who knows when the traffic will move again?" said the 37-year-old, who was stranded for two nights in the last jam at almost the same location.

A woman at the Inner Mongolian traffic management office said it may take several days to ease the latest jam. "Please do not drive on this expressway," said the official, who also would not give her name.