Railway tunnel builders blast through last rock

With a loud explosion on Sunday in the Hufengling Tunnel, 200 kilometers from Harbin, Heilongjiang province, the final section of rock gave way, marking a major step in the construction of a high-speed railway in Northeast China.

The 8,755-meter tunnel on the Harbin-Mudanjiang line is the longest of those that have been built in regions with extremely low temperatures - in this area as low as -40 C.

During its construction, builders dealt with many difficulties, not least the cold.