Wellington's rush hour traffic heading east in the evening is moving at an average speed of just 27kmh these days, thanks in large part to the bottleneck at the Basin Reserve.

The commuter crawl across Wellington is not quite down to a snail's pace, but at less than 30kmh it might as well be for frustrated motorists.

New figures show drivers' average speed along State Highway 1 during the evening rush - 4pm to 6.30pm - from Wellington's CBD to the airport in Rongotai is just 27kmh.

The journey into central Wellington from the eastern suburbs in the morning - 6am to 10am - is almost just as bad, with motorists creeping along at an average speed of 30kmh.

ROBERT KITCHIN/STUFF Traffic backs up along Ruahine St, between Wellington's CBD and the airport.

The congestion figures were included in a report by Greater Wellington Regional Council, which also revealed carbon emissions from transport have shot up by 7 per cent since 2013.

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The report, which evaluated how the region's transport network was performing, also examined the average speeds in and out of Wellington, during peak periods, along two other main commuter routes.

Mark Coote The Poplar Ave interchange for the Kapiti expressway, looking west, including the section of road that will drop from 80kmh to 50kmh under a New Zealand Transport Agency proposal.

It found the average speed for those coming into the city from Waikanae via SH1 in the morning was 61kmh, and 59kmh heading back the other way at night.

Meanwhile, those heading in via SH2 from Upper Hutt were hitting an average speed of 52kmh in the morning, and 60kmh when they left in the evening.

Automobile Association policy research manager Peter King said the expectations of Wellington drivers were "not that great" and there was an increasing frustration about journey times.

SUPPLIED Automobile Association policy research manager Peter King says Wellington drivers aren't optimistic about how things are going.

In a survey conducted in June, 60 per cent of its Wellington members said congestion had become significantly worse in the past five years, while 42 per cent expected it to get significantly worse in the next five years.

"So they're not that optimistic about how things are going," King said.

"It's pretty obvious people are fairly frustrated and they don't expect things to improve."

Congestion relief is on the way north of Wellington in the form of the $630 million Mckays to Peka Peka expressway, due to open next year, and the $850 million Transmission Gully motorway scheduled for completion in 2020.

But central Wellington is a different story. Plans to build second Mt Victoria and Terrace tunnels, as well as widen Ruahine St and Wellington Rd, were stalled indefinitely when the Basin Reserve flyover failed to get resource consent in 2014.

Barbara Donaldson, the council's new regional transport committee chairwoman, did not respond to requests for comment on Wednesday.

Barry Mein, director of the Let's Get Wellington Moving programme, which is investigating solutions to the city's traffic woes, said the public would be consulted on a range of options for solving the problem in early 2017.

In 2016, the Wellington region's transport emissions amounted to 1140 kilotonnes of carbon dioxide, or 2.26 tonnes per capita - a 7 per cent increase.

The council report said this was mainly due to an increases in diesel consumption, with sales rising by 18 per cent in the past five years across the Wellington region.

The increase was concerning, given transport emissions had decreased by 7 per cent between 2005 and 2013.

Regional councillor Sue Kedgley, chairwoman of the environment committee, said electrifying the bus network needed to be done as a matter of urgency.

"If we're going to get serious about climate change, we need to reduce car dependency by encouraging people to take public transport, as well as trying to encourage uptake or conversion to electric cars and getting rid of our diesel buses."