Wellington's Regional Council is blaming a perfect storm of new operators, buses, routes, driver shortages and design failures for the shambolic introduction of new bus services a year ago.

Photo: RNZ / Emma Hatton

While reliability has since improved to 92.5 percent of services leaving on time, it is still just 89.2 percent in the east and west of the city.

The regional council's chief executive, Greg Campbell, told Parliament's Transport and Infrastructure Select Committee this morning the national bus driver shortage and a lack of bus lanes in Wellington were the two biggest road blocks to fixing the capital's bus system.

He said there was nobody to replace drivers who called in sick.

"This leads to cancelled services, often in the peak morning commute and it always seems to be - not on a day like today - but on a wet and windy day," Mr Campbell said.

"While not large in absolute numbers, any cancelled service is not just frustrating for commuters, they can cause subsequent services to be overcrowded or too full to pick up passengers."

Metlink had a joint recruitment campaign underway with bus companies to deal with the shortages, he said.

The challenges around bus priority and dedicated lanes would be addressed as part of the early delivery of the Let's Get Wellington Moving programme, but that work was complicated due to Wellington's hilly geography and constrained layout, he said.

National list MP Nicola Willis said she wanted to know who was accountable for the problems, when around 30 bus services are cancelled each day.

"What accountability measures have you had on your management for failing to deliver on [previously agreed] targets [of 95 percent reliability]? 'Cause let me be very clear it has had a significant impact not only on Wellingtonians everyday, but on the reputation of the bus service and the reliability of it," Ms Willis said.

The regional council's acting chair, Barbara Donaldson, said "that's part of their performance but what we expect them to do is to be working very hard, reporting to us and we're monitoring that all the time".

"We're working with all our partners, so that includes the bus operators, to help them overcome issues in driver recruitment... and we're working with Wellington City Council on bus priority measures, so we're all accountable but we certainly are just working as hard as we can," she said.

While the focus was on fixing the problems rather than attributing blame, "staff are in no doubt that this is part of their performance," Ms Donaldson said.

If everyone was accountable, that meant nobody was actually accountable, said Ms Willis.

Mr Campbell told Ms Willis he rejected that the region was still in the situation that she described.

"You've told a story several times today already about the state of the bus network. I'm afraid you can create a story, I don't have that luxury as chief executive. I have to work within the facts, and I've presented the facts today," Mr Campbell said.

"I do accept dismay at particular circumstances customers experience, and if you really focus it, it comes down to driver shortages and congestion."

Transport Minister Phil Twyford has rejected the Opposition's call for a Crown Observer to help solve Wellington's bus woes.

"At this stage, I have no intention to put in an observer. This thing is fixable and GWRC need to do their job," Mr Twyford said.