Auckland rail workers who are members of the Rail and Maritime Transport Union are set to take industrial action to make a ban on overtime.
As a result, train services in Auckland will be affected for the next three weeks thanks to a reshuffle in the train timetable.
The move will see thousands of Auckland commuters waiting twice as long for a train during peak hour.
Auckland Transport's Chief Transport Services Officer Mark Lambert says about 10,000 Aucklanders catch the train during peak hours from 6.30am to 8.30am and 4.30pm and 6.30pm.
He adds that there will be a 20-minute wait from tomorrow onwards during those times.
The rail network faces further strain over coming weeks with thousands of university students returning to study.
The Rail and Maritime Union says it has safety concerns about a proposal to give train drivers the responsibility of opening and closing doors.
Rail and Maritime Transport Union organiser John Kerr says, "Transdev and Auckland Transport aren't budging on a driver-only operation, which will severely compromise passenger safety."
He also says the people driving the trains will be responsible for passenger assistance and security.
“With train managers on every train, the public can feel safe knowing a skilled, uniformed member of staff is never far away," says Kerr, "An overtime ban will affect services, so we hope management will start listening".
The Onehunga and Pukekohe weekday train services will have the usual timetable and bus and ferry services are not affected.