South Korean authorities said Wednesday that they would summon two subway officials as part of the investigation into the train crash in Seoul that left hundreds injured last week.

An eastbound train rear-ended another at Sangwangsimni Station on Line 2 on Friday allegedly due to a traffic signal error, injuring more than 240 passengers, with seven in serious condition.

The Seoul Metropolitan Police Agency will question two Seoul Metro traffic signal managers over whether they accurately reported the signal problem to superiors before the accident, officials said.

One of the two signal managers had acknowledged the signal problem 14 hours before the accident, and purportedly reported to the office. But the subway operator allegedly ignored the issue, the police said Tuesday in an interim report.

The investigation crew also confirmed that the first train did not report its 90-second departure delay at Sangwangsimni Station, where it was hit by the incoming train.

The police are analyzing documents and traffic signal data that it seized from the Seoul Metro offices and a private firm to look into the signal data entry process, the authorities said.

It was revealed that the Seoul Metro revised the traffic signal data last month to speed up train traffic near Euljiro 1(il)-ga Station, five stops from the accident site. The data entry work was not conducted by the subway operator but by a private company.

As part of efforts to ease public concerns over train safety, Seoul Mayor Park Won-soon conducted a safety check Wednesday morning in a round trip on Line 2 from City Hall Station to Seongsu Station, which included Sangwangsimni Station.

“The control center needs to be able to see all the details of each train,” Park told the subway officials. “(The office) trusted the automatic control system but it can sometimes make mistakes. Double or triple safety measures should be readied.”

Seoul City vowed to carry out a special safety inspection on all subway lines until July.

Officials and experts will replace any faulty power supply equipment, worn-out train tracks, subway control systems and security devices, the city said.

By Lee Hyun-jeong (rene@heraldcorp.com)