New RMIT modelling predicts that cutting speed limits from 50km to 30km on residential streets would deliver safer cycling routes and only add 1 minute to average car trips.
The Centre for Urban Research study rated every road in greater Melbourne for traffic stress, factoring in speed limits, existing bicycle lanes, government trip data and traffic volumes.
It then modelled the change from 50km to 30km. At 50km, low-stress streets made up about one-third of the average bike trip, but at 30km that increased to two-thirds.
Lead author, Dr Afshin Jafari, said lowering speed limits would be a quick and cheap way to improve cycling safety.
“Installing physical barriers on every local street would be ideal, but it’s expensive and slow,” he said.
“Slowing down vehicles is a cheap and effective way to improve safety while we wait for longer-term infrastructure upgrades.
“Slowing traffic makes bicycle riding less stressful, encouraging more people to choose bikes as a safe and viable mode of transport.”
And Dr Jafari says the benefits would be felt most in outer suburban areas rather than the inner city.
“Outer suburban streets often don’t even have footpaths, let alone other infrastructure to separate bicycle riders and pedestrians from motorists,” he said.
If a person is hit by a car travelling at 50km/h the chance of survival is about 10%, whereas at 30km it’s 90%.
Victoria has altered its speed limit lows to allow local councils to set 30km limits, following on from a successful trial in the City of Yarra. While other cities have also changed some city streets to 30km, no Australian council or state has enacted a widespread change to 30km.
Other countries and cities have applied 20m/30km residential and city streets more broadly including Wales, the UK, Spain and The Netherlands and cities in many Scandinavian countries.
‘Modelling the impact of lower speed limits on residential streets for cyclist level of traffic stress and car travel time in Greater Melbourne’, is published in the Journal of Cycling and Micromobility Research. DOI: 10.1016/j.jcmr.2025.100085
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