Road workers, construction crews and other NSW transport staff will walk off the job, unhappy with their below-inflation pay rise.
Transport for NSW workers will down tools for 24 hours from 6am on Thursday.
The Australian Workers' Union says staff are outraged by the NSW government's three per cent pay offer, saying it represents a significant step backwards in living standards with inflation at 5.1 per cent and predicted to rise.
"These men and women worked tirelessly to keep our state moving during recent bushfires and flood catastrophes," AWU NSW branch organiser Cameron Wright said on Wednesday.
"During the pandemic they put on their work gear and went out into an uncertain world while the rest of us were locked down.
"And now (premier) Dom Perrottet wants to tell them all to cop a pay cut. It's just not going to fly.
"The average road worker is being told to feed their family with significantly less."
The strike comes on top of a swathe of industrial action by other frontline workers this year including teachers, paramedics, rail staff and nurses.
Unions have given Transport for NSW management a commitment members will respond to genuine emergency situations to keep the public safe during the state's flood crisis.
The workers will rally outside the front gates of major depots at 9am on Thursday, including at the Sydney Harbour Bridge and Civic Park in Newcastle.
