Railroad operations connecting Seoul and the port city of Busan returned to normal after train traffic was effectively halted for more than five hours when a piece of drilling equipment fell onto the tracks, the Korea Railroad Corp. (KORAIL) said Monday. The state-run corporation said it has cleared a 20-meter piece of drilling equipment used to make an underground causeway near Uiwang Station, south of the capital city, that fell across three of the four tracks at 4:25 a.m. Because no trains were running at the time there was little damage, KORAIL said, but many people had to use buses or other forms of transportation for part of the morning since only one track was open. \"Emergency repair teams sent to the accident site removed the wrecked equipment and trains have been running normally as of 9:50 a.m.,\" KORAIL said, adding it will start a probe to determine exactly why the construction equipment fell over. The equipment was turned off and being moved when it collapsed. The country\'s KTX bullet train services, however, were not affected since these trains use a different rail line, the corporation said.