Sydney commuters could be hit with further light-rail shutdowns as a union refuses to rule out additional strikes in its pay dispute with network operator Transdev.
Inner-city trams were brought to a standstill in a 24-hour shutdown on Wednesday, as the Rail, Tram and Bus Union ramped up pressure on the transport company for better pay and increased sick leave for workers.
The light-rail stoppage is due to finish just after midnight on Thursday, but it could be extended as union members deliberate their next move.
Transdev has called in buses to replace the light-rail services.
RTBU tram and bus secretary David Babineau said the union apologised to the public for interruptions, but it would not rule out further strikes.
"We reflect what our members want to do and our members are wanting to stand up for what they believe they deserve," he said.
"If they decide that they want to go longer than that will be up to them."
Transdev recently offered workers a six per cent pay rise in the first year, followed by four per cent increases in the following three years, but no additional sick leave.
RTBU members rejected the offer, calling for a 23 per cent pay increase over four years with an extra five days of sick leave.
Mr Babineau said workers needed the extra sick days to help manage fatigue as workers' rosters often switched from mornings to afternoons and evenings.
"If they don't get a decent sleep and they're expected to manage their fatigue, if that means calling in sick, it's burning sick days," he said.
Other union-led disruptions will stay in place during the industrial action if a deal is not struck.
They include reduced tram speeds, as well as workers refusing overtime and the wearing of uniforms.
Transdev previously said the company was committed to negotiating with the union and it hoped a resolution could be reached soon.
Customers were told to plan ahead as the disruptions might continue indefinitely.