Aucklanders are being warned to expect all-day traffic congestion - even if enough money can be raised for pressure-relieving transport schemes such as the $2.86 billion city rail tunnels.
A new report from Auckland Transport predicts significantly worsening congestion between morning and afternoon traffic peaks after 2021 under existing budgets providing $34 billion of transport funding over the next 30 years.
Even if that can be boosted to $59 billion to pay for all desired projects with extra revenue, such as from road tolls or higher parking levies - also serving to reduce travel demand - it warns that its programme will not keep ahead of traffic growth in the second and third decades of the planning horizon.
The budget compares with $7 billion spent on transport around Auckland since 2000.
About two-thirds of the desired $59 billion would be to pay for new and existing roads compared with $19 billion for public transport and $760 million for walking and cycling facilities.
Not only will drivers face ever-lengthening morning traffic queues, but those trying to get about the region in what is called the inter-peak period of 9am to 3pm are in line for a dramatic increase in congestion from about 2023 under the "committed" $34 billion funding scenario, says the report.
The "integrated transport programme", adopted late yesterday by Auckland Transport, predicts that between-times congestion will overtake morning snarl-ups from about 2033 as extra freight hits the roads - meaning a redefinition of peak travel times.
It says that by then, 25 per cent of all road travel between 7am and 3pm across Auckland will be in excessive congestion, compared with about 12 per cent during morning peaks now, and 5 per cent in the inter-peak. It does not include data about evening travel, but that is unlikely to be much better, if any.
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The report says that although some congestion must be expected in "a thriving, successful city of two million people", levels forecast for Auckland by 2041 are well above those now experienced in centres such as Sydney and Melbourne with their already considerably larger populations.
Even under a "fully-funded" programme, the report fears inter-peak congestion will start overtaking morning delays by about 2038.
It says that although better public transport can relieve pressure on roads for trips to and from work, it is less able to help between times.
But it believes a planned extension of higher frequency bus routes over the next three years - operating from 7am to 7pm every day of the week - should make some difference.
Both the Campaign for Better Transport and city council transport chairman Mike Lee have been urging Auckland Transport to also increase inter-peak and weekend trains to stem a decline in rail patronage.
Transport commentator Matt Lowrie is questioning the validity of the modelling behind the report, noting on a blog site hosted by the campaign that there is nowhere else in the world where roads are busier between morning and afternoon commuter runs.
He is "embarrassed" that even supposing alternative transport schemes can be fully funded to reduce reliance on cars, the report predicts a 17 per cent rise in Auckland's carbon dioxide emissions by 2041, against a target reduction of 49 per cent.
• $60b Desired transport funding to 2041
• $34b What has been committed so far from available sources
• $45b- $50b Expected funding before resorting to new sources such as tolls or higher parking levies to reduce road travel demand
• $7b Transport spending in Auckland since 2000