West Japan Railway Co. has found a total of 2,049 defective points in the tunnels of the Sanyo Shinkansen Line, it was learned Tuesday.
JR West has inspected all the 142 tunnels, which total 280 km in length, between Osaka and Hakata, Fukuoka Prefecture, following mishaps on June 27 and Monday.
In the June accident, some 200 kg of falling concrete ripped a gaping hole on the roof of Hikari No. 351 as it passed through the Fukuoka Tunnel in Hisayama, Fukuoka Prefecture.
On Monday, a chunk of concrete measuring 6 cm by 12 cm and weighing roughly 200 grams was found to have broken off an elevated bridge supporting a portion of the Sanyo Shinkansen track between Himeji and Aioi in Hyogo Prefecture.
Although no one was hurt in the incidents, JR West considered the cases serious and conducted an emergency checkup.
According to railway officials, 2,049 defective joints were found, but there are no traces of cracks or raised wall surface at those places, and no immediate fear of accidents.
Because 87 percent of the defective joints were discovered in areas within the jurisdiction of its Hiroshima office, the officials said they see the possibility that faulty concrete or construction was involved.
They said the company plans to check all the tunnel walls using hammers before the end of his month.