Restricting cars and trucks to 30km/h would be the norm for neighbourhood streets under proposed laws being unveiled on Wednesday.
The change comes amid rising fatalities on Australian roads in the face of a national goal to eliminate all road deaths and serious injuries by 2050.
While nine out of ten people die when hit by a vehicle driving at 50 km/h, nine in ten people survive when hit at 30 km/h, safety advocate Jennifer Kent says.
Inner-city Melbourne and parts of suburban Sydney have adopted the lower limits but Dr Kent views the varied approaches across Australia as unfair for children, parents and the elderly.
"Why should my son be safe walking to school but my cousin who lives in Brisbane is not?" the spokeswoman for advocacy group 30 Please told AAP.
"It's not fair that some people's lives are more important than others, so why wouldn't we do this on a national scale."
Kobi Shetty lives in an inner Sydney area where the speed limit is more than 30 kilometres an hour.
"I see a lot of neighbours who live near me drive their kids to school less than a kilometre," she told AAP.
"They drive their kids to school because they don't feel safe letting them walk or cycle."
That perspective has helped push the NSW Greens MP to introduce a bill to enact a statewide 30km/h limit on residential roads.
She says it's the "most impactful" way to protect motorists, cyclists and pedestrians from road accidents as drivers will be forced to travel slower in high traffic areas.
If adopted, NSW would follow Germany, Italy, Spain and the UK in lowering limits to such levels.
In those areas, communities have seen a 40-per-cent reduction in fatalities on roads that have these limits, Ms Shetty said.
The cost to motorists was meanwhile between 30 seconds to one minute for each journey, research suggested.
"Most people would understand that it's worth spending an extra 30 seconds sitting in a car and saving a life," Ms Shetty said.
Premier Chris Minns however doubled down on opposition to 30 km/h caps first aired in 2024.
"I think that's too slow," he told reporters on Wednesday
Ms Shetty's bill will be debated at a later date.
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