Yet another problem has emerged on the troubled Hong Kong-Zhuhai-Macau bridge project, with the Highways Department confirming seven piles have been replaced.

The Apple Daily reported Sunday that a contractor had replaced seven large-diameter piles, each tens of meters long, at its own cost.

The name of the contractor, the reasons for the replacement work and the exact location were not clear, although one of the replaced piles is for the artificial island that will host the boundary crossing facility next to Chek Lap Kok. The 3m diameter pile had been buried to a depth of 60 or 70 meters.

One frontline engineer told the Apple Daily that the reclamation work was feeling the effects of tides, with the result that the pile bases were being slowly twisted in the mud.

Other experts quoted said the problems were probably the result of both the rushed construction process and complex geological factors.

Reportedly the cost of the rework amounted to HK$10 million, which is not huge in a project already costing around HK$90 billion and in which more than more than 1000 large-diameter piles have already been installed.

But it is just the latest in a series of problems on on the bridge scheme that has blown its budget and deadlines because of engineering issues and industrial accidents. Legco voted another HK$5.4 billion to the bridge at the end of January, despite filibustering by pan-Democrat members.

The bridge was due to open in early 2016 and is now officially slated for late 2017, but the actual start date is likely to be well after that.