Reduced speed limits in residential areas not only protect cyclists and make cycling less stressful but also do not cause traffic delays for motorists, a new study from Australia suggests.

As part of the new study, researchers from the Royal Melbourne Institute of Technology (RMIT) modelled reductions of the speed limit from 50kph (31mph) to 30kph (18mph) in residential areas of Greater Melbourne and rated traffic stress levels across the city.

They found that a reduced speed limit doubled bike usage on “low-stress” streets, while the targeted imposition of a lower speed limit resulted in “minimal” journey delays for car drivers of no greater than a minute.

This negligible impact on journey times, the researchers say, was due to lowered speed limits largely being applied on local streets instead of larger, ‘busier’ roads designed to maximise the flow of traffic.

20mph sign
20mph sign (Image Credit: CC licensed by EdinburghGreens via Flickr)

The Australian study, published in Cycling and Micromobility Research, also found that decreased speed limits reduced traffic stress for both drivers and cyclists, and built on existing research that found “purpose-built, bicycle-specific infrastructure is associated with a lower risk of crash and injury for cyclists”.

The researchers concluded that improved cycling infrastructure and safer roads resulted in the biggest cultural shifts among “interested but concerned”, risk-averse cyclists.

In other words, these policy changes do not just cater to an existing demographic of cyclists, but play a key role in encouraging more people, such as children and less confident cyclists, to ride their bikes.

“Slowing traffic makes bicycle riding less stressful, encouraging more people to choose bikes as a safe and viable mode of transport,” the study’s lead researcher, Dr Afshin Jafari, says.

This “build it and they will come” approach has also been seen in other major cities around the world such as Paris and Toronto, and in London during the recent Underground strikes.

Female cyclist in London wearing a red coat on a steel road bike
Female cyclist in London wearing a red coat on a steel road bike (Image Credit: Simon MacMichael)

Jafari added that most existing cycle lanes on 40mph or 50mph roads were highly stressful for less confident cyclists, discouraging them from cycling.

Following the study’s publication, the director of the Institute for Sensible Transport, Dr Elliot Fishman, pointed out that cycling rates in Australia remain low, accounting for only two per cent of commutes to work – and had barely shifted in the past 20 years.

“The main reason people are choosing to make those trips by car rather than cycling is that they don’t feel safe riding a bike,” Fishman told the Guardian.

Calling for a standard 30kph speed limit on all residential streets in Australia, Fishman said: “If you get hit by a car travelling at 50kph, you’ve only got a 1.5-in-10 chance of surviving. If it’s going 30kph you’ve got a nine-in-10 chance.”

> Cyclist casualties down 28% and 900 fewer road injuries since 20mph limit introduced in Wales – but driving instructor still brands change a “total disaster”

This latest study adds to the growing volume of research and data detailing the advantages of reduced speed limits – but the policy remains politically controversial.

Last month, we reported that new data revealed that the number of cyclists injured or killed in road traffic incidents in Wales has fallen by more than a quarter since the roll-out of the country’s ‘default’ 20mph speed limit.

In September 2023, amid widespread political debate and acrimony, the Welsh government introduced a default 20mph speed limit on urban and residential roads (where most, though not all, dropped from 30mph), increasing the approximately 870km of 20mph roads in Wales to 13,000km.

And according to figures released by the Welsh government, between the policy’s rollout in September 2023 and the end of March, 348 cyclists were killed or injured on all roads in Wales, down 28 per cent compared with the 481 reported casualties from April 2022 to September 2023.

The number of cyclists seriously injured also decreased by 30 per cent during the same period. North Wales, which saw 94 per cent of its 30mph roads switch to 20mph, recorded the biggest decrease in total casualties.

The success of Wales’ reduced speed limits, and their significant impact on casualty figures, has been branded “proof that slower speeds on our roads save lives” by active travel organisations such as Cycling UK, who described the policy as the “single most significant and positive change we’ve ever seen in any nation in the UK”.

Earlier this year, Cycling UK also called on the rest of the United Kingdom to implement similar lower urban speed limits, while a recent active travel report commissioned by the Bikeability Trust and Living Streets charities urged the government to introduce default 20mph speed limits for motor vehicles in all urban areas.

> Cyclists call for 20mph limits on all Oxford roads by 2029 – but bus company says lower speeds would lead to congestion, longer journey times, and “less attractive” travel

The scheme hasn’t been without its critics, however. Despite the promising road safety figures, question marks continue to hang over the future of Wales’ default 20mph speed limit on residential roads, as several councils currently consider whether more roads could be switched back to 30mph.

The Conservative shadow secretary for transport in Wales, Peter Fox, also claimed that – despite causality numbers dropping – the party still held concerns about the policy, arguing that it confuses drivers and that a “more sensible” approach should be adopted.

“While we welcome any decrease in road casualties, these figures don’t tell the whole story. Our concern remains the way the 20mph speed limit has been implemented,” Fox said earlier this year.

“The Welsh Labour government’s default approach has created confusion and frustration for drivers and their current review must address these implementation issues and ensure a more sensible and effective approach.”