Users of Auckland's Northern Gateway toll road who don't pay up within five days will pay more than double the current administration fees from next month.

The Transport Agency yesterday announced an increase in the charge for late transactions, from $2.20 to $4.90, from August 1 as well as new fees for payments at road-side kiosks and by phone.

The new levies will be on top of existing tolls of $2 for cars and motorbikes and $4 for trucks and buses - amounts which will remain unchanged.

Those who fail to pay within 28 days of receiving toll notices already face $40 infringement fines on top of late fees and the tolls themselves.

The agency yesterday confirmed that it would charge 40c on top of tolls for drivers making payments at kiosks and $3.70 for those paying through its Palmerston North-based call centre.

But it said the new charges would be absorbed into the late fee of $4.90 for those not paying up within five days.

Motorists with pre-paid sinking accounts and automatic top-up facilities against credit cards or bank accounts will not be liable to any administration fees, as the Transport Agency is trying to cut costs by encouraging that method.

Neither will those who pay online within five days of travelling on the 7km road between Orewa and Puhoi.

The agency will also close its call centre at weekends to help reduce its average toll collection cost of 74c to a target of 65c.

But it will extend hours slightly on week days, from 8am to 6pm, compared with 8.30am to 5.30pm now.

Collection costs for each transaction now range from an average of 13c for online payments and 30c for those with pre-paid accounts, to 54c at kiosks and $3.85 through the call centre.

The Automobile Association, although supporting the new administration charges, is disappointed the call centre is to be closed at weekends. "I think that is most unwise and the AA will be having discussions with the Transport Agency as to whether there is a better way to do it," spokesman Simon Lambourne said.

His organisation had no problem with the agency recovering its costs by introducing the new fees, or increasing those for late payments.

"However, motorists will be expecting high levels of service delivery. If they are going to charge motorists to use certain payment methods, these have to be efficient and effective," Mr Lambourne said.

"If you're a tourist visiting for the Rugby World Cup and it's the weekend and you call the 0800 number and get told it's closed, that's not really an adequate solution."

Mr Lambourne welcomed the Transport Agency's intention to take recidivist toll evaders to court, saying it should have started doing that well before writing off an unpaid debt of $537,134 at the end of last year.

"The poor management of the toll road which has resulted in $500,000 being written off because it wasn't collected in time is not the right signal which should be sent to the more than 90 per cent of motorists who are paying the toll," he said.

"It's unacceptable to use the road and not pay. It's a debt road - it's been built and funded through debt."