Advanced equipment to be used on metro line 3 construction

In order to improve the accuracy of metro subway tunneling, advanced directional equipment with the highest accuracy in China was recently introduced and utilized for a survey of the construction of the Guiyang Metro Line 3, according to local media reports on Dec 26.

In survey, the measurement accuracy of underground traverse work is related to the tunnel breakthrough error -- and high-precision construction is of supreme importance.

The contractors brought in what is known as a gyro northfinder fiber optic compass. It is a cutting-edge measuring device to find the true north of a given position.

Combined with known control points on the ground, it can provide accurate direction values for the control points of underground traverses. The accuracy of the advanced instrument is one to three times that of conventional equipment.

Technicians from a third-party survey project tested its accuracy in the line 3 tunnel and it lived up to expectations.

As a result, the new technology will be used in the construction of the Guiyang rail transit project.