Temporary screens may have to be fixed to an unfinished pedestrian bridge over motorway traffic to Westhaven, on Auckland's waterfront so it can be opened.

Although the motorway tunnel beneath Victoria Park has been open since March, carrying three lanes of northbound traffic, the neighbouring bridge from the Jacob's Ladder steps beneath the St Marys Bay cliffs stands unused - because of faulty panels.

The Transport Agency says it is still waiting for results of an investigation into why "isolated" hair-line cracks appeared on 10 of 206 acrylic panels fixed to the $7.9 million bridge.

Meanwhile, it is considering whether to attach temporary screens to the structure, so it can be opened to the public before a permanent solution is found.


It says tests have satisfied it that the 10 lanes of traffic passing underneath are in no danger from faulty panels.

But it remains unable to say when the bridge can be completed, as the cause of the cracks has yet to be identified, and it does not know how that may affect the structure's long-term serviceability and appearance.

Agency spokesman Ewart Barnsley said the panels had been made in the United States and patterned acrylic film, which would give the bridge a distinctive Maori fishing net appearance, was made in Europe.

"One area of investigation is how well these two elements adhere together," he said.

Mr Barnsley said the agency would have a clearer indication of when the bridge could be completed, and whether that was possible within the original $7.9 million budget, once investigation results were known.

He disclosed that one option under consideration was completing the bridge with temporary screening so it could be opened to the public without too much extra delay.

The agency has described the bridge as a critical link in a network of walking connections it has upgraded as part of the $406 million Victoria Park tunnel project, which also included widening the motorway along St Marys Bay to the harbour bridge.

It would restore a historic link between land and sea, and its draped net appearance would recall the past importance of the area to Maori as a fishing ground.

A walkway has also been developed as part of the project through St Marys Bay from Beaumont St to Pt Erin.

Mr Barnsley said although the acrylic panels were made in the southern United States, the agency could not confirm a suggestion they were produced by convict labour in a prison.

Regardless of that, he said there was no suggestion of poor manufacturing quality control.