Wave-like undulations have appeared on the new southbound span of the Yuli Bridge on Provincial Highway 9, worrying road users, but the Directorate General of Highways says the structure is safe and only the expansion joints need repair.

• Since the new southbound span opened to traffic last April, drivers have reported over the past six months or so that the deck rises and falls unevenly, with noticeable jolting when crossing the expansion joints and height differences of up to two centimetres in places.
• The bridge, which spans the Xiuguluan River, is one of only two bridges in the world crossing an active fault between the Eurasian Plate and the Philippine Sea Plate; its eastern side is lifted two to three centimetres each year by crustal movement.
• The Directorate General of Highways says the wave-like profile was part of the design from the outset, intended to accommodate the rising plate, and that monthly monitoring since the bridge opened has found deformation within the expected range.
• The height differences at the expansion joints are attributed to recent high temperatures softening the material, which was then deformed by tyres; repairs are under way in sections.

Outlook: Once the expansion joint repairs are complete, the road surface will return to an even finish, but the undulations in the deck caused by the rising plates will remain over the long term. The northbound bridge is still under construction.