The vital role infrastructure plays in reducing road fatalities and serious injuries is one of the key messages from the recently released PIARC/World Road Association Road Safety Manual.

This second edition of the manual is the outcome of a project undertaken by the World Road Association (PIARC) as a contribution to the United Nations Decade of Action for Road Safety, launched in 2011 with the aim of helping countries build capacity for managing road safety.

Victorian-based Australian Road Research Board (ARRB) was chosen to draft the manual.

The safe system approach

Lead author and ARRB Principal Research Scientist Blair Turner says the manual puts forward a strong case for all countries to adopt a safe system approach, which puts the onus for safe roads on factors additional to the driver.

“It really does turn around how we look at road safety,” he explains. “There’s an increasing awareness that there are different elements that can all act together to help us improve safety.

“Road users are obviously important – we need to drive safely. But also the road itself, speeds, and the vehicle types are part of that equation. It’s all part of the system working together to give a safe outcome.

“Previously, we’ve said a large percentage of crashes are caused by human error – that’s still true, but as road managers, even if the crash is caused by driver distraction, there’s a role that road can play to make sure the outcome isn’t a fatal or serious injury.

“If you are distracted on a country road, you might lose your lane position, run off the road and hit a tree. It’s part of a human error, but road agencies have a role to play in making sure there’s no trees that are too close to the side of the road, or that there’s proper barriers in place.

“Humans do make errors, so it’s about putting in place a broader system that caters for those errors when they do happen.”

Best-practice road infrastructure saves lives

Turner says, until now, the role infrastructure plays in road safety has been under-stated.

“This document is really key in terms of showing the importance of road infrastructure in the role of road safety,” he says.

“It’s really the first time we’ve very clearly articulated that infrastructure is so important. Often in our global guides we focus on the humans that cause the problem and almost stop there. What we’re doing here is turning that around and saying, ‘we recognise there is a human error issue on our roads, but infrastructure has a really, really important role to play’.

“We actually call upon evidence in this case from Sweden that shows that very clearly. It’s still the case that 90% of crashes are caused by human error, but we also know that the outcome, once that crash starts to happen, is most significantly influenced by infrastructure. Fatigue is a human error, but we can put in place infrastructure to prevent a crash happening, or if it does happen, ensure that the outcome is not as severe as it might otherwise be.

“It means when problems do occur on the road, they won’t result in death and serious injury.”


The manual outlines the actions that can be taken to deliver the greatest road safety benefit.

“We did a lot of work about what our really effective road safety treatments are,” Turner says.

“For instance, if there’s a high-crash problem at an intersection, the default position in the past has been, ‘let’s just throw a sign up and say intersection ahead’.

“That’s certainly got some benefits for improving safety, but we’ve found over the years that crashes still continue even with that sign in place. Now we’re saying, ‘look, a long-term perspective is let’s see if we can afford to put in roundabout, which is the safer option’.

“Similarly, on the side of the road we’re putting in barrier systems if people do run off the road.”

However, Turned recognises that best practice can mean top-dollar, an often-difficult proposal for cash-strapped local governments.

“A lot of the times we can’t afford to put in place the high-cost treatments, but at least knowing about those treatments is really important,” he explains.

“It’s just trying to turn around the philosophy. We can’t always afford to do this and we need to manage our limited resources, but it’s to make people aware of what the really effective treatments are.”

Integrating asset management and road safety

Turner says managing assets with a focus on road safety can deliver great benefit/cost ratio, giving the example of putting in a road-shoulder.

“We often do that to maintain the long-term integrity of the road – if vehicles are moving to the edge of the road it might start breaking it up if there’s no shoulder,” he says. “We know the cost benefit from that is for every dollar spent, you might get $4 benefit, so that’s a fantastic investment.

“But, there’s also a safety benefit for doing that. If you’ve got a shoulder on the side of the road and people stray off from their lane, it means they can recover and continue driving without a crash occurring. When you bring the benefit from that in as well, for every dollar spent that’s $8 benefit. That’s without spending anything extra.

“Road surfacing is another example of that, where if you’ve got a good road surface, it’s going to have less cracking and less deterioration, but you’ve also got better surface friction and that’s a benefit for safety and for asset management.”

A proactive approach

“Previously, what we’ve done in road safety is we’ve waited for crashes to happen and then we’ve acted,” Turner says. “That’s the blackspot study type approach, where we wait for a pattern to form and that’s still working for us quite well in Australia – but we do know now that less than half of our crashes happen in black-spots, and the vast majority of fatal and serious crashes happen in a more scattered fashion.

“We’re moving now towards an approach where we take a more proactive assessment of the roads, and that’s based on a bunch of tools we’ve developed around the world over the last five to 10 years.”

This is done by investigating the design elements of a road, Turner says. “At really simple level, a straight bit of road is safer than an extreme curve on a road,” he explains. “We’ve done research, and we know exactly the amount of risk attached to that factor.

“We’ve done that same research across all the different design elements on the roads. Based on that research, we’re able to calculate reasonably accurately where crashes will occur based on the design of the roads. The most modern approach is bringing together those predictions, but also the existing crash locations, and using the best of all information to predict where crashes will happen.”

That research can also be used to predict the benefit/cost ratios of infrastructure or safety treatments.

Turner says earlier interventions mean the typical locations for crashes are changing.

“We’re not getting the clusters of crashes that we used to, we’ve tackled those really low-hanging fruit locations where there perhaps was a cluster,” he says.

“We need to be a bit more innovative in assessing likely crash locations, and we talk about systemic approaches – if we know that a certain road type or feature is very dangerous, we go out and change that feature over a period of time as budgets allow.

“We’ve done this historically as well – we know that a Y intersection is less safe than a T intersection, so over many years we’ve actually removed almost all Y intersections in our road networks. It’s really an extension of that same approach.”

One of the greatest challenges encountered in drafting the manual was its broad readership – the practices needed to be applicable from Australia to India, Turner says.

“The target audience is quite varied– we’re looking right through from low and middle-income countries right through to high-income countries, so that’s a massive audience in terms of the breadth and how people need information,” he explains.

The manual will soon be translated into French and Spanish, and will inform road safety globally.

The manual is available for download from the PIARC website.