Wednesday's bus driver strike in Wellington has ended, but the drivers' union says there will be more industrial action later this month in the form of free trips on some services.

Nineteen Wellington bus routes were cancelled between 9am and 3pm on Wednesday, affecting commuters between 8am and 4pm as NZ Bus drivers attended a meeting to discuss their proposed new contracts.

The Tramways Union members – of which there are about 200 employed by NZ Bus – are unhappy at being asked to work part-time shifts, resulting in fewer hours.

Union secretary Kevin O'Sullivan said drivers agreed at the meeting to a fare strike from January 28, meaning bus services would operate but commuters would not be charged.

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"Up until recently we've had a pretty good relationship with NZ Bus, but in recent months there's been a real push from the company to undermine the people who work there," O'Sullivan said.

"If NZ Bus take[s] a sensible approach to part-time shifts, as the members are asking them to, this dispute will settle."

NZ Bus has been approached for comment.

A Metlink spokesman said there had not been a notable spike in complaints about buses during the strike hours, although it seemed likely a lot of people were inconvenienced.

It appeared Wednesday's strike had a greater impact on commuters than a similar one staged by Tranzurban's union members in October, the spokesman said.

On that occasion, almost 97 per cent of services ran on schedule.

"Metlink apologises for the inconvenience and the impact the strike is having on customers while they make alternative travel arrangements," it said in a statement earlier on Wednesday.

Drivers' terms and conditions were not retained as part of negotiations overseen by Greater Wellington Regional Council for new bus operator contracts last year.

The council's sustainable transport committee chairwoman, Barbara Donaldson, said the decision to strike was disappointing for commuters.

"We continue to urge both parties to come to a resolution as quickly as possible and we will do all we can to inform customers about the availability of bus services at the earliest opportunity."

BUS ROUTES AFFECTED BY FARE STRIKE

2, 3, 12, 12e, 13, 14, 18, 18e, 20, 21, 22, 28, 30x, 31x, 33, 34, 35, 36, 37