A history of isolation is set to end for the Tibetan county of Metok after construction workers successfully blasted through the last section of a mountain highway tunnel Wednesday.

Teams from the two ends of the tunnel, part of a planned highway that will link Metok to the outside world, met at 10:28 a.m. after using 152 kg of explosives to blast through the remaining center section at 10 a.m.

The 3,310-meter-long Galongla Tunnel, built at an altitude of 3,750 meters, was a crucial project in the Metok Highway, said Weng Mengyong, Deputy Minister of Transport.

The "extremely complex" meteorological and geological conditions had made the construction work arduous and difficult, said Weng.

Metok County, with a population of 11,000, is China's last county with no highway link.

Snow and rain make the mountain roads impassable for nine months of the year, and the walk out of the mountains can take about 10 hours.

"It was a life-threatening adventure every time I crossed the mountains out of Metok," said Zhou Haitao, a government official who once worked in Metok for five years.

Zhou reckoned he had walked more than 2,000 km around the county in his time there.

"Mudslides and avalanches are common on Galongla mountain," Zhou said.

The 117-km Metok Highway, linking Metok and Bome counties, will shorten the time dramatically as the journey through the tunnel will take just half an hour.

"I can finally join my family during Spring Festival holidays," said Fang Hong, a Metok-born member of the Menba ethnic group who works outside the county.

"My family would not let me go home at Spring Festival for fear of avalanches," Fang said. "With the tunnel, we won't worry any more."

Fang must wait another year before the route is completed as 90 km of highway between the end of the tunnel and Metok County has yet to be built.

Metok County, in Nyingchi Prefecture, is located at the lower reaches of the Yarlung Zangbo River and at the eastern section of the Himalayas.

Covering 3,400 square km, the Metok area descends steeply from north to south with environments changing from icy mountain slopes to tropical rainforests.

Metok's economy relies mainly on agriculture, but transporting produce out of the county is difficult without roads for cars or lorries.

The poor infrastructure, particularly the inadequate highway system, had hindered economic development in Tibet in the past, said Baima Chilin, chairman of the government of Tibet Autonomous Region.

With efforts from the central and Tibetan governments, Tibet had built a highway network of 58,000 km, which had boosted economic development and enhanced social stability in the region, he said.