OSAKA -- A plastic drain gutter inside a Sanyo Shinkansen Line tunnel in Yamaguchi Prefecture was found sagging along the tunnel wall Monday, disrupting the operations of several trains and forcing West Japan Railway Co. to suspend nine bullet train runs, JR officials said.

According to officials, the driver of a bullet train bound for Hakata, Fukuoka Prefecture, reported seeing something resembling an overhead light dangling along the wall of the Habu Tunnel in Shimonoseki, Yamaguchi Prefecture, at around 8:45 a.m. The rain pipe was spotted some 500 meters from the tunnel's opening on the Shin-Shimonoseki side.

An investigation found that about 3 meters of the drainage trough were out of position.

On another Sanyo Shinkansen Line train, a passenger reported to the conductor at around 9:35 a.m. that a strange noise could be heard under the floor. A subsequent check led to further train delays.

The inspections, which began Oct. 25, are scheduled to be completed Dec. 15 and expected to affect close to 60,000 passengers.

Monday's runs on the Sanyo line were delayed by up to 10 minutes as the trains slowed to 70 kph to let inspectors check the tunnels. There have been several other incidents involving damaged tunnels on shinkansen lines since a concrete slab fell on the roof of a moving bullet train in Fukuoka Tunnel in Hisayama, Fukuoka Prefecture, causing a temporary halt to services in June.

Other cases have involved tons of concrete or rock found to have fallen onto the tracks, or trains that have actually hit large chunks of rock weighing several hundred kilograms.