Auckland bus drivers are considering industrial action, saying violence against them has to stop before someone is killed at the wheel.

Unions say drivers fear for their safety after two recent stabbings on the city's buses, the latest an attack on a driver who spent two nights in hospital at the weekend.

The 62-year-old accused will face a judge-alone trial in May.

Meanwhile, unions are speaking out for the drivers, whose contracts prevent them from talking to the media themselves.

It comes amidst a public transport crisis in Auckland, where nearly 1000 trips a day are being axed because of driver vacancies.

First Union organiser Hayley Courtney said now more than ever, bus drivers feared retaliation from agitated passengers.

"They are fearing for their safety and their wellbeing. Every day they go to work they are fearing they might not come home to their families. They're feeling extremely vulnerable every day."

She talked to drivers at an Auckland bus depot on Monday morning, some telling her they had been punched while at the wheel.

Courtney said drivers wanted immediate action from Auckland Transport, Auckland Council and the bus operators.

"We're extremely frustrated with the circumstances. We're now in a crisis in the bus industry in terms of their safety. Drivers or any workers in New Zealand, but particularly bus drivers in this instance, shouldn't come to work every day fearing for their lives and their safety."

Courtney said the change was urgent.

"There is thought of a stop-work meeting. We'd like to have a meeting with these companies, and the union members and get them to really address their fears to the managers and Auckland Transport. Something has got to happen before someone dies."

'Spike' in aggression since Covid-19

Both NZ Bus and Auckland Transport said they were concerned about an increase in abuse towards bus drivers.

Auckland Transport executive general manager of safety, Stacey van der Putten, said there was a range of security measures on buses, including panic alarms, CCTV and roving security and transport officers.

"We have been working with our operators and the unions on a number of measures over the last couple of years. Coming out of Covid we did see a spike in levels of threats and aggression."

She said abuse and violence against bus drivers were extremely concerning and the agency was continuing to work with the sector on safety.

Together with NZ Bus, Auckland Transport was also trialling screens for drivers on two buses.

NZ Bus chief operating officer Stephen McKeefry said drivers, increasingly being subjected to abuse and anti-social behaviour, are being extensively consulted on the design and use of the screens.

"We are extremely concerned about driver safety and are doing all we can to protect our drivers and reduce the risk, including the trialling of safety screens and undertaking de-escalation training.

"Buses are also GPS-tracked and [have] panic alarms fitted. Our drivers provide an essential public service and do an incredible job to navigate the city's busy streets and keep passengers safe."

He said when a bus driver was attacked on Saturday, a senior manager from NZ Bus provided immediate assistance and was in close contact with him as he recovered.

"We are also in contact with the driver's family offering assistance where we can," McKeefry said.

"While incidents like this are fortunately very rare, our drivers are increasingly being subject to abuse and anti-social behaviour which is completely unacceptable."

Call for more transport officers

Meanwhile, the Tramways Union has asked for security to be made available on an inner city bus route, CityLink, which looped from Britomart up to Karangahape Road and back.

National secretary Gary Froggatt said the route was known to be problematic.

"We can't have a policeman on every bus, which we'd like. Auckland Transport has, I understand, around 70 transport officers but we hardly ever see them on the bus - they're mainly on the trains and the ferries - and I think more needs to be done in that area."

Auckland Transport said its transport officers were deployed to routes and bus stops where needed, as needed.