BEIJING, Dec. 29 -- China Railway Corp put seven high-speed lines into service in southern, central and western China on Saturday. The national high-speed railway network, consisting of eight major lines - "four horizontal and four vertical" - has taken shape with the seven new lines.

China's high-speed railway now exceeds 10,000 kilometers - nearly half of the global total - and is expected to hit 18,000 km by 2020.

Shaanxi province's Xi'an-Baoji line runs at 250 km per hour. The other six are 200 kph. They are slower because they traverse trickier topography.

It took six years for construction workers and engineers to build these historic high-speed railways across the diverse and often-challenging landscapes. This time was spent grinding twisting terrain into smooth routes.

Travel time from Beijing to Guilin, a picturesque city in the Guangxi Zhuang autonomous region, has been shortened from about 26 hours to 10.5 hours. It now takes 3.5 hours to go from Guangdong province's Shenzhen to Fujian province's Xiamen by bullet train - eight hours fewer than before. And travel time from Shanghai to Shenzhen has been cut from 18 hours to fewer than 12.

The high-speed rail along the coastlines of Zhejiang, Fujian and Guangdong - connecting Shanghai, Xiamen and Shenzhen - is crucial to the integration of the three economic hubs: the Yangtze River Delta, the Fujian city clusters and the Pearl River Delta.

The number of passengers from Guangdong to North China has risen 20 percent this year, thanks to the 2,298-km Beijing-Guangzhou high-speed railway - the world's longest. It has carried nearly 100 million people its first year.

It is significant that four of the seven new lines are in Guangxi. Guangxi railway construction office deputy director Luo Wei said the high-speed railway network in Guangxi has extended over six years from nothing to 1,137 km - a 10th of the national total.

Guangxi, with 230,000 square kilometers and 50 million residents, is China's first ethnic autonomous region to be integrated into the national high-speed railway network before the Xinjiang Uygur, Ningxia Hui, Inner Mongolia and Tibet autonomous regions.