There are saying that construction company SK E&C knew the risks of collapse for Bujeon-Masan double-track railway tunnel (in section 2 Nakdong 1 tunnel). There are claim that SK E&C ignored the warnings to keep up with construction schedule. SK E&C deny such claims.

SK E&C is a very big successful construction company in Korea with many international work. SK E&C built many prestige important projects in world for example Eurasian tunnel in Istanbul, Turkey.

The Bujeon-Masan railway project is important to connect Bujeon in Busan and Masan in Changwon. It is a private investment project of Smart Rail. The construction is made by a consortium of 3 companies: SK E&C (leader company. builds sections 1,2), Samsung C&T (sections 3 and 4) and Hanwha E&C (sectin 5).

Original completion date of project was February 2021 but Smart Rail ask for extension until end 2022 almost two years delay. Investigation of tunnel collapse is very slow.

The collapse on Bujeon-Masan tunnel occurred only in Section 2 built by SK E&C in March 2020. It caused a large sinkhole 20 meter deep. There is investigation for cause of collapse. Initial investigated started by private company Smart Rail. Many people did not trust private company investigation. Now investigation is made by Ministry of Land, Infrastructure and Transport.

For under construction Nakdong 1 tunnel collapse, the Korean Tunneling Environment Association already say Korean Geotechnical Society report point to possibility of construction errors. Lee Chan-woo, vice chairman of the Korean Tunneling Environment Association, said, “The groundwater runoff management standard was set too loosely without considering the ground conditions during the design.”

Korean news media psnews say unnamed SK E&C employee say collapse was because of high pressure CCG grouting pressure. SK E&C enforced ground by grouting to stop groundwater but pressure damaged main tunnel. Publication say experts say interior of the tunnel also should have been reinforced with in-pit grouting to balance grouting pressure of ground.

There are saying that SK E&C there were signs of problem and a construction partner told SK E&C to stop work but their concerned not listened. Work continued until collapse.

SK E&C says there is no proof collapse is because of a mistake. If SK E&C is found guilty, the company have to pay huge compensation.  Financial institutions which lent money to the business operator, Smart Rail very unhappy about slow investigation pace for tunnel collapse and they began to recover the loan and one month ago, the insurance company Munich RE has refusing to extend the construction insurance. (I don't know whether it extended in past weeks).