Seoul Mayor Oh Se-hoon (right) inspects the section of the connecting ramp at Seongsu Bridge where a pavement step has formed and checks the safety management status of the facility on July 10. [Seoul Metropolitan Government]
Seoul Mayor Oh Se-hoon (right) inspects the section of the connecting ramp at Seongsu Bridge where a pavement step has formed and checks the safety management status of the facility on July 10. [Seoul Metropolitan Government]

The Seoul Metropolitan Government plans to strip the road surface on the southern entry ramp of Seongsu Bridge and inspect the ground beneath it. The city said the move is intended to ease public concern over a pavement step that has recently drawn attention.

Seoul said Monday that it will conduct on-site tests Wednesday, with external specialists in structural engineering and soil mechanics taking part to assess the condition of the structure beneath the pavement and the load-bearing capacity of the ground.

The step has formed not on the bridge itself but on a section of retaining wall built up with compacted soil. The on-site tests are designed to verify whether the ground retains sufficient load-bearing capacity.

To carry out the tests, the city will fully close the ramp from 9 p.m. Wednesday to 6 a.m. Thursday. The closure covers the southern ramp leading from the Olympic Expressway's Dongho Bridge-to-Jamsil direction onto Seongsu Bridge. One of the four adjacent Olympic Expressway lanes will also be partially restricted.

Once the tests are complete, the city will repave the stretch from the ramp entrance to the bridge approach to reduce jolting felt by passing vehicles and improve ride stability and comfort.

The city said it will analyze the on-site test results alongside an ongoing precision safety diagnosis to assess the facility's condition and, if necessary, draw up repair and reinforcement measures.

The city had previously identified the roughly 9-centimeter step during a precision safety diagnosis and had been monitoring it. Because no additional settlement had been recorded since 2016, officials concluded there was no structural safety concern — but public unease over the step has grown in recent weeks.

In response, the city launched a joint inspection with external experts on July 9 and conducted ground-penetrating radar surveys the following day, finding no anomalies that could affect safety and no sign that the step was widening, it said.

"Inspections to date have confirmed there is no structural safety problem, but we will conduct on-site tests in parallel to put citizens' minds at ease and do our utmost to manage the facility with safety as the top priority," said Choe Jin-seok, head of the Seoul Metropolitan Government's Disaster and Safety Management Office.

The city also said it recently identified a step of about 8 centimeters on the northern entry ramp of Dongjak Bridge, but assessed it as the result of long-stabilized settlement and structurally sound.

A city official said the step at Dongjak Bridge had been identified during a precision safety diagnosis in 2023 and had been checked periodically since then, adding that a comprehensive survey of Han River bridges launched July 9 had also confirmed its stability.

The official added that the cause of the step on the Dongjak Bridge ramp was the same as at Seongsu Bridge — long-term settlement of the soil section at the junction between the bridge structure and the earthen approach — and that no further progression had been observed, with the condition now stable and posing no structural concern.

The city is conducting a comprehensive survey of bridge sections across the city to dispel concerns over the Seongsu Bridge ramp step and plans to announce its findings and any countermeasures in due course.

The city noted that all steps identified so far are on roads resting on soil and retaining walls, not on elevated bridge spans, and that the absence of change over an extended period indicates the risk of collapse is low.


ken@heraldcorp.com