A much more detailed description of what happened in the accident, correcting earlier accounts, was published in the December 2011 report of the official investigation. The first train D3115 was stopped not by losing power as a result of the lightning strike, but was stopped by the signal system, the Automatic Train Protection (ATP). The lightning had struck a trackside LKD2-T1 signal assembly, burning out its fuses, and violating the rule that it should be 'fail-safe'. This had caused an incorrect indication in the control center that the track section containing train D3115 was unoccupied (the so-called 'green signal'). The driver He Li of train D3115 worked to override the ATP and, after more than seven minutes of waiting, at 8.29 p.m. he got the train moving again, overriding the ATP. As train D3115 entered the next section of track, where the track circuits that indicate the presence of the train were working correctly, the control center now saw that the track section was occupied. But driver Pan Yiheng of the following train D301 had already been given instructions to proceed onto the section of track where D3115 had been stopped, when the control center had a false indication that the track was unoccupied. Despite a message from the control center that D301 should proceed with caution, less than half a minute later train D301 running at collided with train D3115.
