Auto-scanning total stations working on China’s expressways

Spectra Precision‘s Focus 35 robotic total stations are helping build the world’s largest expressway network. For instance, the Focus 35, with its time-saving automatic scan template, is checking the cross-section quality of the twin Nan Kunshan tunnels for the new six-lane Shazhan S14 regional highway.

Excavation under Nankun Mountain for the twin tunnels, each 4.1 kilometers (km) long and each capable of carrying three lanes of vehicular traffic, began in September 2016.

In the current second phase of construction, the Focus 35 is being used to gather data that will be used to compare the as-built tunnels to the design specifications to determine what adjustments to the tunnel surfaces may need to be made.

The Focus 35 was selected for the scanning work because it offers a streamlined and efficient workflow that yields significant time-savings, the company said. The workflow of a conventional total station requires time-consuming manual scanning followed by export to a separate post-processing function after which a DXF file is generated.

The Focus 35, with its Trimble Access Tunnel software, saves significant time because it automatically scans and directly generates DXF reports for submission to the contractor to check over-break and under-break values, the company said.

When completed, the new six-lane 800-km Shazhan highway will connect Shantou and Zhanjiang, two important coastal cities in southern Guangdong province. The contractor for the Nan Kunshan tunnels is ChangDa Highway Engineering Co. Ltd.