CHENGDU - Sichuan province started laying tracks on Sunday for the first high-speed railway in mountainous southwest China, where ancient visitors called a trip there harder than that to heaven.

The railway, which will link cities including the cities of Mianyang, Deyang, Chengdu and Leshan, stretches 312 kilometers across the Wenchuan earthquake struck areas.

Workers will lay down tracks about six kilometers a day, and work will be completed by the end of 2013. High-speed trains will run at a designed speed of 200 kilometers per hour.

The total investment for the line will reach 40.5 billion yuan ($6.4 billion). There are 30 million residents along the railway.

The railway is expected to make transportation more convenient in China's southwestern regions neighboring a few Southeast Asian nations.

China opened the world's first high-speed rail line in areas with extreme low temperatures on Saturday, bringing the country's high-speed rails in operation to 8,600 kilometers, the longest globally.