Meeting in the Middle

从山的两侧开始钻一条57公里的长隧道，几乎没有任何偏差在中间会议，这是一项真正具有挑战性的任务。需要高度精确的测量工具来成功完成该项目。

测量到毫米精度
At the tunnel site, the surveying consortium VI-GBT started measuring in 1996, when construction work began 20 years ago. The surveying engineers set up a basic network with 20 reference points. For this task, they used total stations, or optical measuring devices, and GPS, or satellite navigation solutions from Leica Geosystems, a global company with Swiss roots and a tradition of nearly 200 years.

The drilling began not only at Erstfeld (north portal) and Bodio (south portal), but also at three intermediary points where side channels joined the main tunnel: Amsteg, Sedrun and Faido. In Sedrun (1,405 m high), a vertical tunnel 800 m long was drilled down to the main tunnel so construction workers could push north as well as south from that point.

During tunnel construction, surveying and measuring tasks had to be repeated every 400 metres (437.4 yards). In order to make sure the tunnel was precisely on course, the surveyors had to check coordinates of the reference points. In addition, the exact height had to be measured with levelling devices – also from Leica Geosystems.

“When we broke through in the middle of the tunnel on October 15, 2010, the two tunnel sections met with a deviation of only 8 centimetres or 3.1 inches, whereas 25 centimetres or 9.8 inches would have been tolerated,” said Ivo Schaetti, a surveying engineer of VI-GBT. He explains that surveying tunnels is very demanding due to temperature changes, humidity and dust. “Thankfully, we could always rely on the accuracy of the surveying solutions from Leica Geosystems,” Schaetti adds. “They are very precise. You can measure a distance of 400 meters with accuracy of less than a millimetre or 0.03 inches.”

监视隧道上方的大坝
在整个施工期间，隧道上方三个人造湖的周围环境需要监视：Curnera，Nalps和St. Maria。隧道的建设很可能会影响其大坝的稳定性。该监视也是使用Leica Geosystems的工具进行的。从2000年到2015年，全自动设备对整个隧道建筑的大坝进行了监视。

Leica亚博5分钟快三 Geosystems产品经理Falko Henning说：“我们的总站监测了棱镜安装的最小运动。”“快乐，没有发生异常运动。”在施工期间没有重大延迟，隧道将按计划开幕。

A Swiss tradition
Leica Geosystems has a rich history in Switzerland. From its origins with Kern & Company founded in 1819 in Aarau, today the industry leader in measurement technology operates globally serving customers in many segments, including engineering, construction and mining.

“Looking back on a tradition of nearly 200 years, we’re honoured to once again take part in a significant milestone in Swiss history by providing the surveying and monitoring resources to successfully open the Gotthard Base Tunnel,” said Juergen Dold, Leica Geosystems CEO. “With a commitment to Swiss quality and a global outlook, we will continue to innovate and support professionals around the world achieving feats of engineering like this tunnel.”