ENGINEERS must keep a close eye on the SDR in case it sinks even further, a road expert warned today.

The Argus revealed yesterday how part of the new road built over a rubbish tip has sunk by two to three centimetres.

Contractors say it is safe and have started making repairs - but admit that the road could sink further.

A 100-metre stretch of dual carriageway near the Big W store that is already open to traffic is being pulled up and resurfaced.

Contractors Morgan Vinci are putting in a concrete slab to spread the weight of the road over the rubbish tip.

Mike Rowe, a civil engineer based in Bridge Street, Newport, said: "If there is rubbish on the site you have to be very careful. The level of compaction depends on how long it's been there and what it is.

"I'm very surprised this has happened. The concrete slab will spread the load, but what can happen then is the whole of the slab can settle further. "A drop of over two centimetres would be felt at higher speed and it's starting to get dangerous for traffic going at speeds of 50mph and over.

"I would think that now regular checks are needed. Perhaps checks every three months at first, then every six months. But it has been very well constructed under difficult circumstances."

The 100m-stretch is the only part of the SDR passing over softer ground that was not supported with piles - underground pillars.

Peter Frood, Morgan Vinci project manager for the SDR, said workers were unable to drive the piles down because of overhead cables. He said the concrete slab should stop further sinkage.

Councillor Ron Jones, cabinet member for transport, said the road would be subject to a safety audit before the council took it over.