Busan tunnel route suffers new ground subsidence

Another ground subsidence incident has been reported on a road above the Mandeok-Centum underground expressway, a deep-bore tunnel connecting Mandok-dong in Busan’s Buk-gu District and Jaesong-dong in Haeundae District. The latest case has deepened public concern as Busan city officials have yet to determine a clear cause despite repeated reports of sinking roads since the tunnel opened in February.

The Busan Metropolitan Government said Sunday that a driver traveling near the entrance ramp to the Naeseong underpass in Myeongnyun-dong, Dongnae District, reported at 9:18 a.m. that the road felt as though it was “sinking and rippling.”

Officials from the city’s Construction Headquarters and representatives from GS Engineering & Construction, the project’s contractor, were sent to the scene. Authorities closed two lanes on the Myeongnyun-bound entrance ramp and one exit lane on the opposite side toward Gyodae while an inspection was underway. The closures caused heavy traffic congestion across parts of Dongnae District during the holiday weekend.

The Mandeok-Centum underground expressway is a 9.6-kilometer, four-lane tunnel that opened Feb. 10. Billed as Busan’s first deep underground roadway, it directly links Buk-gu and Haeundae-gu and cuts travel time by about 30 minutes. Construction began in November 2019, with total project costs reaching 791.2 billion won, including 89.8 billion won in state funding, 112.9 billion won from the city government and 588.5 billion won in private investment.

Reports of subsidence began surfacing soon after the road opened. On April 5, cracks and partial sinking were discovered at four locations near the Naeseong underpass and at two sections near the Suyeong Riverside Underpass heading toward Haeundae District. The following day, another shallow sinkhole was found on the Banyeo-dong-bound side of the Suyeong Riverside Underpass.

At the time, Busan officials pointed to the possibility that backfilling work following tunnel excavation had not been properly completed. The city carried out a two-week ground-penetrating radar survey in affected areas but found no signs of underground voids or other major structural defects.

Kim Hyo-sook, head of the Busan Construction Headquarters, said parts of the road appeared to have sunk slightly again Sunday, leading crews to remove damaged pavement and repave the area. “This was not a situation where underground cavities suddenly collapsed like a sinkhole,” Kim said. “We are not conducting another large-scale backfilling operation.” The city said repairs would be completed before all traffic restrictions are lifted at 4 a.m. Monday.


부산=강성명 기자 smkang@donga.com