Fluorescent road cones, detours and a jaded worker flipping a stop-go sign are the bane of driving, so motorists will be pleased to know more than 58 per cent of roadworks on the nation's highways are finished early.

But some projects had months added to their scheduled completion date.

The New Zealand Transport Agency says it is working hard to make sure roadworks continue to be finished early.

Of the 58 national highway roadworks projects completed in the past three financial years, 34 were finished early, 10 were on time and 13 were delayed, according to figures provided to the Herald from the NZTA. The most delayed project was the Tirau intersection of State Highway 1 and SH5, which was delayed by 175 days.


An NZTA spokesman said the delay was caused by design changes.

Continuing with construction over winter would have meant "an unacceptably high risk of travel delays to drivers and compromised the long-term performance of the road".

"A decision was therefore made to construct the project over two construction seasons."

The upgrade of the ramps on Neilson St in Onehunga, Auckland, was delayed by 124 days because a number of power and gas lines were discovered which had not been previously identified, the spokesman said.

On the other side of the coin, the Papakura interchange upgrade, Stage 1, was completed 425 days early.

The spokesman said this was down to "excellent collaboration and teamwork between the project's delivery partners and excellent relationships with stakeholders".

Group manager of highways and network operations, Tommy Parker, said the agency was currently in a "bit of a purple patch" with hitting or even beating deadlines.

"Yes, there are some which are delayed but most of them are coming in ahead of time. We've got good systems, good sign-offs to allow contractors to accelerate works and bring them in ahead of time.

"But it's part of the game that there's some which hit delays."

Mr Parker said the agency was very aware of the disruption projects created, so does everything within its power to get them completed early, which also means they're usually under budget.

But sometimes it just comes down to the weather - the drier the summer, the more days work can be done. And unforseen issues like ground issues or design errors meant some projects took longer than expected.

"We're getting better at realising what can go wrong and mitigate that."

Automobile Association spokesman Barney Irvine said what gets under motorists' skin the most is when they drive past a roadworks project but there doesn't appear to be anyone actually working.

"There's a real frustration around that.

"And of course what it also does is undermines the credibility of roadworks signs - people just stop believing them."

Mr Irvine commended the transport agency on the early completion of most of its projects in recent years.

"Let's keep it up."