BAOTOU, Inner Mongolia - An extension project is underway for a section of the Beijing-Tibet Expressway, a major artery frequently clotted with severe traffic jams.

The Hohhot-Baotou section, located in North China's Inner Mongolia autonomous region, has faced constant traffic jams, which sometimes stretch about 100 kilometers and last for days.

The extension project was launched this summer to mitigate congestion by enlarging the current 4-lane expressway to an 8-lane one, according to the regional transport commission.

Trucks and bulldozers rumble through clouds of dust at the construction sites and laborers work long hours in an effort to finish the project in two years.

"The extension construction is entering its peak season as work will be halted during winter. I work almost 16 hours on the busiest days," said Guo Dongdong, a technician who had just finished measuring the roadbed.

The extension has also brought job opportunities to many locals.

"I work at the extension sites for up to 10 hours a day and can earn 80 yuan ($12.5)," Yang Chundi, a resident of a village near the expressway, told Xinhua.

Yang was laying the roadbed while vehicles, mostly coal-carrying trucks, crawled by in a long queue on the highway.

Surging coal transportation has been attributed to the traffic jams on the expressway, the major road for the country's largest coal-producing region.