East Japan Railway Co. got services back to normal on its Keiyo Line between central Tokyo and the city of Chiba on Friday morning, more than 30 hours after a short circuit disrupted signal systems, shutting down the line for nearly nine hours Thursday and with only partial services after that.

The timetable was restored to normal at around 11 a.m. after 88 trains were canceled earlier Friday, affecting some 49,000 commuters, bringing the number of those affected from Thursday to about 216,000, according to the railroad.

JR East President Satoshi Seino, in a statement, apologized for troubling so many commuters and pledged that the carrier will thoroughly investigate the cause of the incident and do its best to prevent a recurrence.

On Thursday at around 4:20 a.m., fire alarm and extinguishing systems were activated in an underground power transformer facility and signal transmission room at Tokyo Station after a short circuit started a fire, which was quickly extinguished, according to the company.

However, the incident disabled some 60 percent of the electrical circuits in the signal system, which forced the shutdown of the Keiyo Line, JR East said.

The entire line was reopened at 7:55 a.m. Friday, but the number of train runs was restricted. Until then, the part of the line between Tokyo Station and Shinkiba Station in eastern Tokyo was closed for repairs, with trains running only between Shinkiba and Soga Station in Chiba.