NSW commuters are being assured buses are safe following revelations a bus that burst into flames on the Sydney Harbour Bridge was not fitted with a critical safety system.
The 20-year-old bus carrying 30 passengers caught fire at Milsons Point in the middle of peak hour on Thursday evening, causing traffic to come to a standstill as flames and thick smoke billowed from the bridge.
It was one of 265 State Transit Authority buses and 2500 private buses which still need to be fitted with a fire-suppression system - a requirement made mandatory by the Baird government in August last year.
Transport Minister Andrew Constance defended the delay on Friday, saying the government was in the "midst of its rollout" with the last 10 per cent of STA buses to be retro-fitted by the end of the year.
The remaining private buses are due to be fitted by the end of 2017.
"We are doing all we can to see how the program can be expedited for the remainder of the fleet," Mr Constance told reporters.
While fire suppressions systems are "critically important" for buses, they aren't the absolute answer to the issue, the minister said.
So far this year, there have been 36 bus fires on NSW roads, several of which have been major incidents.
Mr Constance said the Office of Transport Safety Investigation, which is looking into Thursday's incident, has not previously identified anything systemically wrong with the state's buses.
OTSI will report back to the government in coming days.
"I want to make it clear that any recommendations they make, we will follow," Mr Constance said.
The Rail, Tram and Bus Union says the government's timetable to fit safety measures "isn't good enough".
"The government needs to get serious and retro-fit all buses with fire suppressant systems to ensure that passengers and drivers are safe," the union's Chris Preston said.
He said Mr Constance needs to take responsibility for this "latest bungle".
The 35-year-old bus driver has been praised for his quick-thinking and selfless actions in getting passengers off the bus.
He was treated for smoke inhalation along with two passengers.
