Inside a tunnel that runs 20 meters underground through Tokyo’s Taito Ward, East Japan Railway Co. in the predawn hours Wednesday unveiled a newly developed vehicle that uses a laser detection system to find cracks on the surface of concrete tunnel walls.
Using blue laser beams that scan about 500 times per second, the system is able to detect cracks measuring as small as 1 mm. It automatically digitizes the data for storage and records the cracks’ locations using videotapes, railway officials said.
Searching for and mapping tunnel wall cracks, which could lead to a fatal collapse, have been painstaking and time-consuming efforts for railway workers.
The new system will enable railways to save time and to examine concrete surfaces far more precisely, the officials said.
The vehicle carrying the system runs along the tracks at a speed of 3.5 kph.
JR East plans to checks all its tunnels — which add up to some 800 km in length — within five years using the new system, the company said.
The deterioration of the concrete in railway tunnels drew much public attention last year when a series of cases involving concrete blocks falling from tunnel walls occurred on the Sanyo Shinkansen Line, operated by West Japan Railway Co.