Proposed highway speed change in Victoria would cost lives, experts warn

Victoria’s Shadow Minister for Roads and Road Safety has defended an election promise to raise speed limits on a key highway, as road safety experts say the decision could cost lives.

Opposition Leader Jess Wilson promised last week that if elected in November, her government would raise speed limits on the Princes Highway and Freeway between Melbourne and Colac from 100km/h to 110km/h.

The Department of Transport's (DTP) current speed zoning policy would need to be changed for the promise to be fulfilled, as it does not allow for the Princes Freeway to be lifted to 110km/h for safety reasons, including the high traffic volume between Melbourne and Geelong. 

Drive understands a 2018 DTP report into raising the speed limit to 110km/h for a portion of this journey determined the move could increase crashes by approximately 25 per cent.

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However, DTP did not provide a copy of this report to Drive upon request.

Danny O'Brien, Shadow Minister for Roads and Road Safety, said the decision to raise speed limits on the Princes Highway between Melbourne and Colac to 110km/h was based on the road's safety classification.

“Our announcement to increase the speed limit on sections of the Princes Freeway and Highway is based on the Princes Freeway’s high safety rating of five under the Australian Road Assessment Program (AusRAP),” O'Brien told Drive.

“This is comparable to Victorian roads that already have a 110km/h speed limit such as the Hume, Calder and Western freeways and highways, as well as the eastern part of the Princes Freeway.”

According to the DTP website, while almost all of the freeway between Werribee and Geelong carries the highest safety rating of five stars, much of the route between Geelong and Colac is currently listed as four stars.

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DTP states that each step up in star rating halves the risk of fatal or serious injury. For example, someone travelling on a four-star road is twice as likely to be killed or seriously injured as someone on a five-star road.

The Director of the National Road Safety Partnership Program, Jerome Carslake, hosted through the Monash University Accident Research Centre, said the possible lives lost by increasing the speed limit were not worth the potential time savings.

“A 10km/h increase in travel speed will lead to a 70 per cent increase in fatalities and a 45 per cent increase in serious injuries,” Carslake said.

“The principles of the Safe System state that no one should be killed or seriously injured through making an error on the road system. Therefore no one should die or be hospitalised simply to save a few minutes from their trip.”

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The claimed time savings from the speed increase have faced scepticism, with Dr Milad Haghani, an Associate Professor of Urban Resilience and Mobility at the University of Melbourne, saying some of the estimates of reduced journey time were impossible. 

“The claimed 15-minute saving between Melbourne and Colac does not appear mathematically possible. Even if the entire roughly 150-kilometre journey could be travelled continuously at 110[km/h] rather than 100 km/h, the maximum saving would be only about eight minutes,” Haghani said. 

“The proposal [to raise speed limits] does not cover the whole journey and retains lower limits in some places, so the realistic saving would be smaller again, even under ideal traffic conditions.

“The claimed five-minute saving to Geelong also looks optimistic. Over the roughly 57-kilometre affected section from Laverton North to Geelong, the theoretical saving is only about three minutes.

“And that assumes uninterrupted travel exactly at the posted limit, so they should even be regarded as upper bounds rather than realistic everyday savings.”

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Dr Haghani detailed studies from America as evidence of the risk of increased deaths that a speed increase would bring.

“On the balance between safety and travel-time savings, it's difficult to say whether the proposal is justified. One of the strongest pieces of evidence comes from a large U.S. study that examined the effects of increased speed limits between 1993 and 2017,” Haghani said.

“It found that every 8km/h increase in maximum speed limits was associated with an 8.5 per cent increase in fatality rates on interstates and freeways, and a 2.8 per cent increase on other roads.

“Those figures provide some indication of the direction and possible magnitude of the safety trade-off, but they should not be interpreted as a prediction of what would exactly happen on this particular corridor.

“Overall, this strikes me as more of a symbolic or cosmetic proposal than a transformative policy. It's unlikely to materially change journey times, but it still comes with a likely modest, but not completely inconsequential, safety impact.”

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This is not the first time the Victorian Liberal-National Opposition has promised to raise the Princes Freeway’s speed limit ahead of an election, having also done so in 2018.

Asked if there were concerns about potential rises in fatalities if the speed limit is increased, and if the Opposition has plans to improve road safety, O'Brien said the stretch of road in question had been upgraded in recent decades – alongside general improvements in vehicle safety technology. 

“Victorians deserve speed limits that reflect the quality of the road, modern vehicle safety standards and common sense,” O'Brien said.

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“This stretch of road has undergone significant upgrades in the past two decades at the same time that vehicular safety technology has also vastly improved.

“The AusRAP ratings make it clear that most of the Princes Freeway and Highway between Melbourne and Colac is five-star freeway standard and therefore suitable for a speed limit of 110km/h with lower limits remaining in designated areas.”

Analysis of crash data by Drive on the Princes Freeway and Highway between Melbourne and Colac suggests a significant number of crashes have continued to be recorded on the stretch of road since records began in 2012. 

Significant data recorded for Serious Injuries appears to be missing for 2021, 2022 and 2023 – and shouldn’t be considered an indication of reduced serious injuries during this period.

The Department of Transport did not answer Drive’s questions regarding the missing data.

Data for 2025 also remains incomplete as monthly crash data is released on a significant delay by the Government.

The figures in the chart above capture recorded crashes on the Princes Highway and freeway from its approximate start point in Melbourne until just prior to entering Colac township. For more detail on each crash data point and its location, explore the interactive charts at the base of this article.