A window crack on a Tokaido Shinkansen bullet train from Tokyo to Osaka forced a temporary slowdown, the operator said late Saturday.

A steel plate on communications equipment in a tunnel in central Japan is believed to have detached and hit a window on the No. 16 car of the Nozomi 317 train Saturday morning, the operator said. Tokaido Shinkansen services were operating as normal on Sunday.

Shinkansen services in Japan, known for their punctuality and reliability, have recently been delayed or halted due to accidents, including an incident earlier this month when train cars separated while in motion.

According to JR Central, the detached steel plate, 30 centimeters long and 60 cm at its widest point, weighing 4 kilograms, was found in the tunnel.

The bullet train decelerated until passengers in the last of its 16 coaches were transferred to other cars.