Photo/Illutration A shield machine to dig tunnels for a planned maglev train (Yuki Shibata)

Tunnel drilling work for a magnetic levitation Shinkansen train line linking Tokyo with Nagoya is running behind schedule, which could eventually delay the planned 2027 starting date.

The tunnel boring work at a depth of more than 40 meters utilizing a shield machine began last fall in Tokyo. But Central Japan Railway Co. (JR Tokai) said on Aug. 9 part of the boring apparatus malfunctioned, which has put excavation work far behind schedule.

The company plans to repair the equipment by the end of December and resume the drilling work by June next year.

Although JR Tokai said that it will not affect the overall schedule at the moment, it is unclear whether the excavation work will proceed smoothly.

If problems are found again, it could delay the starting date of the Chuo Shinkansen Line, which is touted as one of the world's fastest trains. 

The company plans to have the high-speed maglev train in operation between the capital’s Shinagawa Station and Nagoya Station in 2027, with a later connection to Osaka.

Nearly 90 percent of the 286-kilometer maglev line between Tokyo and Nagoya will run through tunnels.

The deep underground work will be conducted in sections of Tokyo, Kawasaki and Nagoya.

In October last year, JR Tokai began an investigation to determine the impact on the surrounding area by horizontally excavating approximately 300 meters from the 90-meter-deep Kita-Shinagawa emergency exit in Tokyo’s Shinagawa Ward.

The company planned to complete the survey in around six months, report the results to local communities, and then dig farther toward Nagoya.

But the drilling work has only progressed about 50 meters as the digging efficiency has not improved since February, according to JR Tokai.

The shield machine removes excavated soil using rotating cutters.

“When we increased the digging speed, part of the machine broke down," an employee said. "Soil stuck to the cutters, making it impossible to dig.”