Forget subsidence, the real cracks in Shanghai's Bund lie behind its veneer

Shanghai's Bund is sinking. Of itself, this is hardly news. The city's most famous street has been slowly settling into its foundations since the row of colonial architecture was first built. Shanghai sits, after all, on a plain of ancient river sludge with the consistency of cold porridge.

In recent weeks, however, the issue has been in focus following local newspaper reports about major cracks appearing on three 'historic buildings' on the Bund, the structures in need of emergency repairs due to subsidence.

At first, the headlines appeared alarming, and threw up images of the city's most recognisable landmark crumbling and being swallowed up by the sludge.

Last March, the city completed a massive three-year renovation of the riverfront, including a major expansion of the pedestrian promenade and a 3.3-kilometre double-deck road tunnel running underneath the length of the street.

Engineers working on the tunnel project spoke about the technical difficulties involved in digging under a stretch of old and in some cases unstable buildings on a soil structure prone to subsidence even when left undisturbed.

Rotting wooden foundation piles were known to extend beneath the buildings, but to unknown depths. Disturbing these, the worry was, could bring the entire house of cards down. It was quite a gamble to take with the city's most marketable tourist attraction.

Talk of Bund buildings cracking up so soon after the project's completion was ominous to say the least. In fact, the three endangered buildings are not part of the iconic strip that features on postcards and promotional materials. Instead, they sit further to the south, bordering a huge swathe of ground flattened as part of the city's seemingly endless urban redevelopment drive.