Tight economic conditions and transport infrastructure improvements are believed to have helped reduce traffic congestion in Auckland to 2004 levels.

Several big motorway projects are believed to have increased the resilience of the roading network by reducing delays caused by peak-time accidents.

Public transport improvements have also been cited.

Although delays suffered by Aucklanders driving to work are slightly higher than a year ago - at an average of 42 seconds for each kilometre travelled - they remain well below a peak of about 54 seconds in 2009.


Delays for workers heading back home have eased to about 32 seconds a kilometre, compared with 36 seconds found in a week-long survey in March last year, according to a report to Auckland Council's transport committee.

But the report points to a persistent bugbear of high variability in journey times on the city's roads, particularly in evening travel peaks.

Travel times noted in the latest survey, for March of this year, varied by an average of 25 per cent from evening to evening on a mixture of motorway and local roads surveyed for the council.

Although that was a considerable reduction from a 35 per cent variation reported last year, it was still higher than that of all five Australian cities for which comparisons are available.

Despite the improvements, the report says Auckland will need to develop enough transport alternatives to cope with a resurgence of congestion after 2021 "as road capacity investments slow down and growth starts to outpace infrastructure investment".

It says that although "vehicle kilometres" travelled in the region in recent years have been rising slowly by about 0.9 per cent a year on motorways and 1 per cent of local roads, capacity on the strategic network has been increasing at a faster rate.

The report also mentions increases in rail capacity and of bus lanes, including the Northern Busway.

It says a flattening off in traffic growth has been common to a number of countries over the past five or six years, and that the use of vehicles is affected by economic conditions and fuel costs.


But it says congestion is still inflicting significant economic and social costs on Auckland, and that land use and transport modelling foreshadows a 46 per cent increase in vehicle use over the next 30 years.

"Traffic congestion in a growing city is identified as a key issue that needs to be managed," the report says.

"The Auckland Plan proposes that this is done through managing demand, traffic management to get the best out of the system, and investment in public transport, walking, cycling , completing the state highway network and selected improvements to roads."

Council transport strategy manager Kevin Wright, who wrote the report, said yesterday that the completion of several large motorway projects appeared to have made a big difference in reducing the variability of trip times.

"In previous years, when there's been an accident on the motorway, it has taken a long time to clear and has had lasting effects," he said.

But motorway widening through the new Victoria Park tunnel and through Spaghetti Junction to Green Lane had made it much easier to clear the way and get traffic flowing again.