UPDATE 5.30pm: Auckland Transport says motorists will not be able to use bus lanes during the eight consecutive Mondays of planned bus driver strikes.

More than 800 NZ Bus drivers are striking over pay negotiations, meaning the company will not run any of its 650 buses on strike days, which begin on Monday.

NZ Bus warns there will be chaos on the city's roads, particularly during the afternoon, but Auckland Transport spokesman Wally Thomas says motorists will not be able to use bus lanes.

"Bus operators who aren't striking will still be using them and we've also managed to arrange alternative services, through other operators, on those major arterial roads that have bus lanes - so the likes of Dominion Road, Manukau Road and Remuera Road.

"The big thing is that school buses run by NZ Bus won't be operating, so potentially thousands of school kids are going to probably be the most affected."

2.45pm: Monday's bus driver strikes will cause a NZ Bus shutdown, with traffic chaos expected in Auckland.

Combined bus union drivers rejected a pay offer from NZ Bus this week and have served notice on the company for eight consecutive Mondays of strikes, beginning next week.

More than 800 of NZ Bus's roughly 1000 drivers are union members.

The company had agreed to a staged pay rise but union members wanted the progression to $20-an-hour to happen more quickly.

NZ Bus chief operating officer Shane McMahon told NBR ONLINE the strikes will shut down all school and urban services on Monday – the company's biggest day – with flow-on effects for other public transport services and motorway traffic. 

The Infratil-owned company runs more than 650 buses across the city covering more than 200 routes.

"Putting that additional load of cars on the road will, unfortunately, clog the city.

"The morning tends to be a bit easier because you'll get a lot of people who know it's happening and they'll leave earlier and spread that peak.

"But in the afternoon, when everyone tries to file out at 5pm I would be expecting delays right across the city."

There will be a "heavy" cost to the company, he says, though he wouldn't say if that will run into the millions of dollars.

However, he says after eight weeks of strikes all of the money budgeted in the rejected pay offer to bus drivers, over 27 months, will be gone.

Not much to talk about

The prospect of talks, in the short term, seems low.

"I don't think there's really much more for us to talk about," Mr McMahon says.

"When the unions have got something they want to discuss we'll meet with them."

NZ Bus is the country's largest urban bus operator, with services in Auckland, Wellington and Whangerei.

It has more than 35 million passenger trips in Auckland a year. 

NZ Bus is wholly-owned by Wellington-based Infratil.

The NZX-listed utilities company owns Wellington Airport with the local city council, jointly owns Z Energy with the New Zealand Superannuation Fund and has a major stake in power company TrustPower.

Infratil shares (NZX: IFT) are up one cent today to $2.16, and have risen 15% this year.

This morning: NZ Bus is apologising in advance to Auckland commuters for a bus driver strike due to start on Monday.

Bus unions doubt any last-minute talks are likely to call off a threatened strike by about 800 drivers on the next eight Mondays and NZ Bus has no alternative plan for thousands of commuters.

In a statement yesterday afternoon, NZ Bus chief operating officer Shane McMahon says the company apologises for disruptions caused by the "irrational escalation" to full-blown industrial action.

The company does not say what aternative arrangements, if any, are being made for the strikes.

Karl Andersen, of First Union, who speaks for the combined bus unions, is gloomy about the prospects of strikes being avoided.

"I can't say there won't be any last-minute talks but I've got some doubts. I think the parties are fairly well embedded in where they are."

Mr Andersen says if the company upped bus drivers' pay to $19.50 immediately, with a rise to $20 within two years, he is "relatively sure" the offer would be accepted.

NZ Bus operates Auckland's Link services, as well as North Star, Waka Pacific and Go West.