Complaints from members include drivers having to work broken or split shifts, a lack of breaks, and a clamp down on pay rates, overtime, and redundancy packages.
First Union is calling for a bus driver industry standard of pay and work conditions such as lifestyle rostering to decrease the pressure on drivers to drive for long periods of time.
"The need for managing overtime hours must also be included in such a standard to manage fatigue," McKean said.
"Drivers are expected to drive for too long with very limited breaks, it is the only industry like it in New Zealand. It's like driving from Auckland to Napier without a single stop, day in day out."
Bus drivers have the right to have a life outside of work, and shouldn't be tired while driving because of work demands," he said.
"Bus companies need to realise they're working with real human beings, not machines, although they're driving what is effectively large machinery with 50-60-odd lives on board."
He said the South Auckland community had been supportive of the strike action.
"Many bus drivers working in Auckland live in the southern suburbs so they're the communities who're being disadvantaged the most. It takes a lot of effort to go on strike, they're angry and so too are their communities, they want their drivers to be treated humanely."
Auckland Transport is advising people to plan ahead, particularly if they are travelling to Auckland Airport, as seven 380 services will be cancelled.
There are 11,000 trips scheduled, and less than 1 per cent will be affected by the strike.
School buses, trains and ferries services are not affected.
Full details of the cancelled services at www.AT.govt.nz/metrochanges