A DISPUTE over Newport's Southern Distributor Road (SDR) could mean more delays, while traffic in the city yesterday ground to a halt.

The road is giving the city council another headache - this time over the design of safety barriers.

The news is a further blow to motorists who yesterday had to endure lengthy hold-ups in Cardiff Road because of roadworks outside Harlech Retail Park.

And a collision involving a car on the M4 between Junctions 27 and 28 at 2pm also caused severe delays for drivers.

The council's row with SDR contractors is over the best design for crash barriers on the central reservation.

The disagreement - if it drags on - could see the opening of the road delayed yet again. Contractor Morgan Vinci has already installed central barriers the length of the 12.5km road, but the council is demanding a different design.

The council said design standards have changed since work on the SDR began. It now wants each stretch of barrier to be supported by more vertical posts than there are at present.

Peter Frood, SDR project manager with Morgan Vinci, said: "There are two details (designs) that the barrier can be built to. Our view is that the one we employ is the right one.

"There's no suggestion the barriers are unsafe. It's just that standards are always being reviewed and updated. It's a complicated issue."

He said the dispute "would certainly have an effect" on an anticipated opening in November if it is not resolved quickly.

But he added: "There is time to change the barriers. It's a case of driving extra posts in. If we resolved this quickly it could be done."

This is the second row the council has had with Morgan Vinci. In September the contractors asked for £50,000 to temporarily open the road for a bicycle race. The council and Newport Unlimited brought the figure down to £28,000.

The £55m Southern Distributor Road is tipped to give a massive boost to traffic flow and regeneration in the city.

It was originally expected to open in June. Then Morgan Vinci shifted the opening to the end of July, blaming the "tidying up" of barriers and roundabouts.

In August the Argus revealed how part of the road had sunk by two to three centimetres, meaning 100 metres had to be pulled up.

And the road suffered another major setback when drainage faults were discovered in September.

The latest estimate for an opening date is late November, which is still ahead of the contracted end date of March 2005.

A spokeswoman for the council said of the barriers dispute: "Newport council and the contractors are working together to ensure all aspects of the SDR are of the highest standard."