Members of the Phyongsong City Battalion increased the tunneling speed 1.3 times by applying efficient drilling and blasting methods and inventing jig and equipment capable of raising the operation rate of wagons.

The Jungsan County Battalion carried out its daily tunneling plan more than 120 percent while reducing the time of removing blast gas and muck and increasing the number of blasting per shift.

Builders of the Pukchang County Battalion and the Mundok County Battalion, too, made a breakthrough by scrupulously organizing shifts and serially drilling and blasting in a reasonable way.