HSR network uses lasers to check all its tunnels for tiny cracks

The High Speed Rail is a vital link in Taiwan’s transportation network. But some of the HSR network tunnels are getting old. The High Speed Rail Corporation is carrying out a major project to scan their tunnels for cracks. Engineers are using lasers to slowly check every centimetre of tunnel for tiny faults. It will take a year to scan all 52 tunnels in the network.

Surveyors in reflective jackets head out late at night, with a 60-kilogram “Laser Tunnel Scanner.” They take the emergency ladder onto the tracks and get on with the job.

The machine emits red laser lights. Advancing at a gentle pace of just 0.7 kilometers an hour, the device takes a 360 degree rotational scan of the tunnel. Any crack longer than half a millimeter will be detected.

Lu Yun-yu
Taiwan High Speed Rail Corporation
Currently, the old tunnels that we need to pay attention to are mainly in the Taipei Metro area, because this is where construction occurred earlier.

The High Speed Rail network is 350 kilometers long, and includes 52 tunnels. In fact tunnels represent about one fifth of the entire HSR line. But automatic scans by machines aren’t enough. Surveyors need to be on site and they have to work at night. It will take a year to scan the entire network nationwide.

Ching Kuo-chang
Taiwan High Speed Rail Corporation
The longest tunnel is Baguashan Tunnel, approximately 7.3 kilometers long. We scan 700 meters a day, so we’ll need about two weeks to complete the scan.

Normal aging can cause cracks to form, as can earthquakes. This is the first time the scanning process has been made public. Engineers hope that by scanning the entire network they can reduce serious risks and ensure passenger safety.