Data from Auckland Transport shows attacks on bus drivers have more than doubled in the last two years.
While 24 fewer incidents overall were reported last year than in 2022, there were more reports of violence against bus drivers than the previous year.
Data provided to RNZ showed AT had reported a total of 24 assaults on bus drivers ranging from minor to severe, as well as more than 50 accounts of verbal abuse in 2022.
In 2023, the organisation reported 51 assaults and more than 120 verbal abuse cases.
Auckland Transport's director of public transport Stacey van der Putten said any assault on a bus driver was one too many.
She said there had been a large spike of incidents reported against bus drivers in mid 2022 and de-escalation was one of the best ways to keep staff safe.
"Being able to de-escalate the situation is the predominate tool that actually does make a fundamental difference," she said.
"It's important to note that we do have CCTV both inside and outside of all of our contracted bus services and they're GPS tracked...
"They have a duress button which automatically connects with operations and dispatch and records the surrounding audio as well, and then they can directly target emergency services and help pull where the situation is arising."
Van der Putten said any new buses in their fleet were fitted with protection shields for the driver and discussions about retro-fitting older buses with protection shields were ongoing.
"That's obviously a conversation we're still having, and is obviously dependent on funding and other things that we're working towards, but making sure that we're working with the industry, as well as the unions, in order to understand what levers work is really important."
Van der Putten encouraged those travelling on public transport to report any instances of anti-social behaviour.
Auckland Transport data shows five more reported instances of intimidation and threatening behaviour in 2023 compared to the previous year.
First Union, which represents a number of Auckland bus drivers, said the violence against bus drivers was an "increasingly disturbing" trend.
Spokesperson Paul Watson said employers needed to take note of the rising numbers.
"The employer's responsibility here really has to pay attention to these alarming statistics that are starting to show this rate of assault that's happening," he said.
The demise of fair pay agreements, which included national standards around health and safety, was a cause of concern for the union.
"We really are quite worried around what's going to happen next," Watson said.
"Without a national standard around this health and safety, and driver protection, we really worry about these incidents of assaults and aggression towards drivers increasing."
He said the cases of violence were far too frequent to dismiss.
"It's happening over a period of time where every day a driver, when they check in for work, get on a bus, and they really don't know what's going to happen during the course of those journeys.
"It's a real worry for them."
Watson said employers and bus companies needed to take greater responsibility around ensuring the safety of their drivers.