More than 3500 buses were cancelled in Wellington last month as the city struggles with a driver shortage and prepares to reduce peak-hour timetables in response.
Difficulties with driver recruitment and retention is affecting operators across the country.
Wellington is at least 60 drivers short, Auckland Transport estimates driver numbers are down by about 10 per cent, while the issue remains an on-going point of pressure in Canterbury.
Cancellations in Wellington have been steadily climbing since January when there were just 545 services which didn't go ahead.
In May, a new record was set with 3159 cancellations followed by 3572 in June.
It's the highest number of cancellations in at least two and a half years and equates to 4 per cent of all services last month.
The situation has been exacerbated by a shortage of at least 60 drivers as well as a stop work meeting on June 23.
At the meeting Wellington Tramways Union members voted to reject the latest pay offer from operator NZ Bus.
It's the latest development in a long-lasting wrangle over their collective agreement, which has resulted in stop-work meetings, a strike, and a lockout.
Metlink general manager Scott Gallacher said the recent escalation of driver shortages is having a particular impact on Wellington City.
In response, Metlink is working with operators on redesigning bus timetables to reduce rush-hour services and increase off-peak ones.
It's hoped this will provide more reliability and consistency for passengers.
Gallacher said parties have agreed to a set of timetable changes in line with actual driver numbers.
"We've identified there is an opportunity to change the way our communities are using public transport following Covid-19 and that will be reflected in the timetable redesign.
"We will be increasing and improving our off-peak services so that our communities have more flexibility for their daily commute and better options to plan their travel outside of the peak."
Meanwhile, Auckland Transport (AT) confirmed operators were struggling to attract and retain drivers, estimating numbers were down by about 10 per cent.
A spokesman said AT was working with operators to understand the extent of the issue and ways to support recruitment plans.
"There are a number of reasons why we are losing drivers. We know some are being attracted to the freight industry because of higher wages and better shift patterns."
Environment Canterbury told the Herald driver recruitment and retention continued to be an ongoing point of pressure.
However, to date, it has not impacted operators' ability to meet scheduled services and timetables.