The Seoul Metropolitan authorities have announced that an inspection by external experts has found that there are no safety issues with the 11cm level difference on Seongsu Bridge.

The Seoul Metropolitan Government has concluded that there are no safety issues with the 11mm difference in height between the bridge and the entrance ramp of Seongsu Bridge, following an external expert inspection. While 32 entrance ramps were inspected across 11 locations on the 22 Seoul highways, the experts found no significant impact on safety.

However, the city plans to reinforce the Seongsu and Olympic Bridge sections, where the difference in height is relatively larger. The Seoul Metropolitan Government revealed the results of the structural, ground, road, and construction expert analysis conducted by 11 experts, including Prof. Kim Sang-ho of Seoul National University's Department of Civil and Environmental Engineering, in a press release.

For Seongsu Bridge, the inspection included surface ground-penetrating radar (GPR) survey, dynamic testing, and exploration of the three side lanes, including the rear ramp. The experts concluded that no unusual signs affecting structural safety were observed. The difference in height is attributed to the anchoring points of the bridge, with the 'anchor shaft' being embedded in the 'base layer' of the bridge and the 'direct anchoring' on the 'soil layer' of the entrance ramp.

This variation is a common occurrence in many bridges due to differences in the structural characteristics of the bridge and the entrance ramp. The anchoring slab, which connects these two structures, has been installed correctly, as confirmed directly. The experts also stated that while most of the subsidence occurred during the construction phase, there is a minimal chance of further subsidence in the long term.

The Seoul Metropolitan Government confirmed that there is still a 11mm difference in height for Olympic Bridge entrance ramps and 15mm for other ramps, emphasizing that they will continue to monitor the situation and reinforce the sections with larger differences in height to address the citizens' concerns.